3ecb - Revision history

OCA at 01:45, 21 November 2024

2024-11-21T01:45:50Z

← Older revision		Revision as of 01:45, 21 November 2024
Line 15:		Line 15:
	<jmolCheckbox>		<jmolCheckbox>
	<scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/ec/3ecb_consurf.spt"</scriptWhenChecked>		<scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/ec/3ecb_consurf.spt"</scriptWhenChecked>
	<scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/~~initialview01~~.spt</scriptWhenUnchecked>		<scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview03.spt</scriptWhenUnchecked>
	<text>to colour the structure by Evolutionary Conservation</text>		<text>to colour the structure by Evolutionary Conservation</text>
	</jmolCheckbox>		</jmolCheckbox>

OCA at 13:00, 30 August 2023

2023-08-30T13:00:39Z

← Older revision		Revision as of 13:00, 30 August 2023
Line 3:		Line 3:
	<StructureSection load='3ecb' size='340' side='right'caption='[[3ecb]], [[Resolution\|resolution]] 1.70Å' scene=''>		<StructureSection load='3ecb' size='340' side='right'caption='[[3ecb]], [[Resolution\|resolution]] 1.70Å' scene=''>
	== Structural highlights ==		== Structural highlights ==
	<table><tr><td colspan='2'>[[3ecb]] is a 3 chain structure with sequence from [https://en.wikipedia.org/wiki/~~Lk3_transgenic_mice Lk3 transgenic mice~~]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3ECB OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=3ECB FirstGlance]. <br>		<table><tr><td colspan='2'>[[3ecb]] is a 3 chain structure with sequence from [https://en.wikipedia.org/wiki/Human_immunodeficiency_virus_type_1_(MFA_ISOLATE) Human immunodeficiency virus type 1 (MFA ISOLATE)] and [https://en.wikipedia.org/wiki/Mus_musculus Mus musculus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3ECB OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=3ECB FirstGlance]. <br>
	</td></tr><tr id='~~ligand~~'><td class="sblockLbl"><b>[[~~Ligand~~\|~~Ligands~~:]]</b></td><td class="sblockDat" id="~~ligandDat~~">~~<scene name='pdbligand=EDO:1,2~~-~~ETHANEDIOL'>EDO</scene>~~, ~~<scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene>~~</td></tr>		</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models\|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution\|Resolution]] 1.698Å</td></tr>
	<tr id='~~related~~'><td class="sblockLbl"><b>[[~~Related_structure~~\|~~Related~~:]]</b></td><td class="sblockDat"><~~div style~~='~~overflow~~: ~~auto; max~~-~~height: 3em;~~'>~~[[3dmm\|3dmm]]~~</~~div~~><~~/td></tr>~~		<tr id='ligand'><td class="sblockLbl"><b>[[Ligand\|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=EDO:1,2-ETHANEDIOL'>EDO</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene></td></tr>
	~~<tr id~~='~~gene'><td class~~=~~"sblockLbl"><b>[[Gene\|Gene~~:~~]]</b~~></~~td><td class="sblockDat"~~>H2-D1 ([https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=10090 LK3 transgenic mice]), B2m, RP23-34E24.5-001 ([https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=10090 LK3 transgenic mice])</td></tr>
	<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=3ecb FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3ecb OCA], [https://pdbe.org/3ecb PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=3ecb RCSB], [https://www.ebi.ac.uk/pdbsum/3ecb PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=3ecb ProSAT]</span></td></tr>		<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=3ecb FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3ecb OCA], [https://pdbe.org/3ecb PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=3ecb RCSB], [https://www.ebi.ac.uk/pdbsum/3ecb PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=3ecb ProSAT]</span></td></tr>
	</table>		</table>
	== Function ==		== Function ==
	[[https://www.uniprot.org/uniprot/HA12_MOUSE HA12_MOUSE]] Involved in the presentation of foreign antigens to the immune system. [[https://www.uniprot.org/uniprot/ENV_HV1MF ENV_HV1MF]] The surface protein gp120 (SU) attaches the virus to the host lymphoid cell by binding to the primary receptor CD4. This interaction induces a structural rearrangement creating a high affinity binding site for a chemokine coreceptor like CXCR4 and/or CCR5. This peculiar 2 stage receptor-interaction strategy allows gp120 to maintain the highly conserved coreceptor-binding site in a cryptic conformation, protected from neutralizing antibodies. Since CD4 also displays a binding site for the disulfide-isomerase P4HB/PDI, a P4HB/PDI-CD4-CXCR4-gp120 complex may form. In that complex, P4HB/PDI could reach and reduce gp120 disulfide bonds, causing major conformational changes in gp120. TXN, another PDI family member could also be involved in disulfide rearrangements in Env during fusion. These changes are transmitted to the transmembrane protein gp41 and are thought to activate its fusogenic potential by unmasking its fusion peptide. Surface protein gp120 (SU) may target the virus to gut-associated lymphoid tissue (GALT) by binding host ITGA4/ITGB7 (alpha-4/beta-7 integrins), a complex that mediates T-cell migration to the GALT. Interaction between gp120 and ITGA4/ITGB7 would allow the virus to enter GALT early in the infection, infecting and killing most of GALT's resting CD4+ T-cells. This T-cell depletion is believed to be the major insult to the host immune system leading to AIDS (By similarity). The surface protein gp120 is a ligand for CD209/DC-SIGN and CLEC4M/DC-SIGNR, which are respectively found on dendritic cells (DCs), and on endothelial cells of liver sinusoids and lymph node sinuses. These interactions allow capture of viral particles at mucosal surfaces by these cells and subsequent transmission to permissive cells. DCs are professional antigen presenting cells, critical for host immunity by inducing specific immune responses against a broad variety of pathogens. They act as sentinels in various tissues where they take up antigen, process it, and present it to T-cells following migration to lymphoid organs. HIV subverts the migration properties of dendritic cells to gain access to CD4+ T-cells in lymph nodes. Virus transmission to permissive T-cells occurs either in trans (without DCs infection, through viral capture and transmission), or in cis (following DCs productive infection, through the usual CD4-gp120 interaction), thereby inducing a robust infection. In trans infection, bound virions remain infectious over days and it is proposed that they are not degraded, but protected in non-lysosomal acidic organelles within the DCs close to the cell membrane thus contributing to the viral infectious potential during DCs' migration from the periphery to the lymphoid tissues. On arrival at lymphoid tissues, intact virions recycle back to DCs' cell surface allowing virus transmission to CD4+ T-cells. Virion capture also seems to lead to MHC-II-restricted viral antigen presentation, and probably to the activation of HIV-specific CD4+ cells (By similarity). The transmembrane protein gp41 (TM) acts as a class I viral fusion protein. Under the current model, the protein has at least 3 conformational states: pre-fusion native state, pre-hairpin intermediate state, and post-fusion hairpin state. During fusion of viral and target intracellular membranes, the coiled coil regions (heptad repeats) assume a trimer-of-hairpins structure, positioning the fusion peptide in close proximity to the C-terminal region of the ectodomain. The formation of this structure appears to drive apposition and subsequent fusion of viral and target cell membranes. Complete fusion occurs in host cell endosomes and is dynamin-dependent, however some lipid transfer might occur at the plasma membrane. The virus undergoes clathrin-dependent internalization long before endosomal fusion, thus minimizing the surface exposure of conserved viral epitopes during fusion and reducing the efficacy of inhibitors targeting these epitopes. Membranes fusion leads to delivery of the nucleocapsid into the cytoplasm (By similarity). The envelope glyprotein gp160 precursor down-modulates cell surface CD4 antigen by interacting with it in the endoplasmic reticulum and blocking its transport to the cell surface (By similarity). The gp120-gp41 heterodimer seems to contribute to T-cell depletion during HIV-1 infection. The envelope glycoproteins expressed on the surface of infected cells induce apoptosis through an interaction with uninfected cells expressing the receptor (CD4) and the coreceptors CXCR4 or CCR5. This type of bystander killing may be obtained by at least three distinct mechanisms. First, the interaction between the 2 cells can induce cellular fusion followed by nuclear fusion within the syncytium. Syncytia are condemned to die from apoptosis. Second, the 2 interacting cells may not fuse entirely and simply exchange plasma membrane lipids, after a sort of hemifusion process, followed by rapid death. Third, it is possible that virus-infected cells, on the point of undergoing apoptosis, fuse with CD4-expressing cells, in which case apoptosis is rapidly transmitted from one cell to the other and thus occurs in a sort of contagious fashion (By similarity). The gp120-gp41 heterodimer allows rapid transcytosis of the virus through CD4 negative cells such as simple epithelial monolayers of the intestinal, rectal and endocervical epithelial barriers. Both gp120 and gp41 specifically recognize glycosphingolipids galactosyl-ceramide (GalCer) or 3' sulfo-galactosyl-ceramide (GalS) present in the lipid rafts structures of epithelial cells. Binding to these alternative receptors allows the rapid transcytosis of the virus through the epithelial cells. This transcytotic vesicle-mediated transport of virions from the apical side to the basolateral side of the epithelial cells does not involve infection of the cells themselves (By similarity). [[https://www.uniprot.org/uniprot/B2MG_MOUSE B2MG_MOUSE]] Component of the class I major histocompatibility complex (MHC). Involved in the presentation of peptide antigens to the immune system.		[https://www.uniprot.org/uniprot/HA12_MOUSE HA12_MOUSE] Involved in the presentation of foreign antigens to the immune system.
	== Evolutionary Conservation ==		== Evolutionary Conservation ==
	[[Image:Consurf_key_small.gif\|200px\|right]]		[[Image:Consurf_key_small.gif\|200px\|right]]
Line 34:		Line 33:
	*[[Beta-2 microglobulin 3D structures\|Beta-2 microglobulin 3D structures]]		*[[Beta-2 microglobulin 3D structures\|Beta-2 microglobulin 3D structures]]
	*[[MHC 3D structures\|MHC 3D structures]]		*[[MHC 3D structures\|MHC 3D structures]]
			*[[MHC I 3D structures\|MHC I 3D structures]]
	== References ==		== References ==
	<references/>		<references/>
Line 39:		Line 39:
	</StructureSection>		</StructureSection>
	[[Category: Large Structures]]		[[Category: Large Structures]]
	[[Category: ~~Lk3 transgenic mice~~]]		[[Category: Mus musculus]]
	[[Category: Margulies~~, D H~~]]		[[Category: Margulies DH]]
	[[Category: Natarajan, K]]		[[Category: Natarajan K]]
	[[Category: Wang, R]]		[[Category: Wang R]]
	~~[[Category: Aid]]~~
	~~[[Category: Apoptosis]]~~
	~~[[Category: Cell membrane]]~~
	~~[[Category: Class i major histompatibility complex]]~~
	~~[[Category: Cleavage on pair of basic residue]]~~
	~~[[Category: Coiled coil]]~~
	~~[[Category: Envelope protein]]~~
	~~[[Category: Fusion protein]]~~
	~~[[Category: Glycoprotein]]~~
	~~[[Category: H-2dd]]~~
	~~[[Category: Host-virus interaction]]~~
	~~[[Category: Immune response]]~~
	~~[[Category: Immune system]]~~
	~~[[Category: Immunoglobulin domain]]~~
	~~[[Category: Lipoprotein]]~~
	~~[[Category: Membrane]]~~
	~~[[Category: Mhc i]]~~
	~~[[Category: Mhc-i]]~~
	~~[[Category: Palmitate]]~~
	~~[[Category: Phosphoprotein]]~~
	~~[[Category: Secreted]]~~
	~~[[Category: Transmembrane]]~~
	~~[[Category: Viral immunoevasion]]~~
	~~[[Category: Virion~~]]

OCA at 11:46, 16 February 2022

2022-02-16T11:46:11Z

← Older revision		Revision as of 11:46, 16 February 2022
Line 1:		Line 1:

	==Crystal structure of mouse H-2Dd in complex with peptide P18-I10 derived from human immunodeficiency virus envelope glycoprotein 120==		==Crystal structure of mouse H-2Dd in complex with peptide P18-I10 derived from human immunodeficiency virus envelope glycoprotein 120==
	<StructureSection load='3ecb' size='340' side='right' caption='[[3ecb]], [[Resolution\|resolution]] 1.70Å' scene=''>		<StructureSection load='3ecb' size='340' side='right'caption='[[3ecb]], [[Resolution\|resolution]] 1.70Å' scene=''>
	== Structural highlights ==		== Structural highlights ==
	<table><tr><td colspan='2'>[[3ecb]] is a 3 chain structure with sequence from [~~http~~://en.wikipedia.org/wiki/Lk3_transgenic_mice Lk3 transgenic mice]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3ECB OCA]. For a <b>guided tour on the structure components</b> use [~~http~~://~~oca~~.~~weizmann.ac.il/oca-docs~~/fgij/fg.htm?mol=3ECB FirstGlance]. <br>		<table><tr><td colspan='2'>[[3ecb]] is a 3 chain structure with sequence from [https://en.wikipedia.org/wiki/Lk3_transgenic_mice Lk3 transgenic mice]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3ECB OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=3ECB FirstGlance]. <br>
	</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand\|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=EDO:1,2-ETHANEDIOL'>EDO</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene></td></tr>		</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand\|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=EDO:1,2-ETHANEDIOL'>EDO</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene></td></tr>
	<tr id='related'><td class="sblockLbl"><b>[[Related_structure\|Related:]]</b></td><td class="sblockDat">[[3dmm\|3dmm]]</td></tr>		<tr id='related'><td class="sblockLbl"><b>[[Related_structure\|Related:]]</b></td><td class="sblockDat"><div style='overflow: auto; max-height: 3em;'>[[3dmm\|3dmm]]</div></td></tr>
	<tr id='gene'><td class="sblockLbl"><b>[[Gene\|Gene:]]</b></td><td class="sblockDat">H2-D1 ([~~http~~://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=10090 LK3 transgenic mice]), B2m, RP23-34E24.5-001 ([~~http~~://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=10090 LK3 transgenic mice])</td></tr>		<tr id='gene'><td class="sblockLbl"><b>[[Gene\|Gene:]]</b></td><td class="sblockDat">H2-D1 ([https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=10090 LK3 transgenic mice]), B2m, RP23-34E24.5-001 ([https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=10090 LK3 transgenic mice])</td></tr>
	<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[~~http~~://~~oca~~.~~weizmann.ac.il/oca-docs~~/fgij/fg.htm?mol=3ecb FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3ecb OCA], [~~http~~://pdbe.org/3ecb PDBe], [~~http~~://www.rcsb.org/pdb/explore.do?structureId=3ecb RCSB], [~~http~~://www.ebi.ac.uk/pdbsum/3ecb PDBsum], [~~http~~://prosat.h-its.org/prosat/prosatexe?pdbcode=3ecb ProSAT]</span></td></tr>		<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=3ecb FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3ecb OCA], [https://pdbe.org/3ecb PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=3ecb RCSB], [https://www.ebi.ac.uk/pdbsum/3ecb PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=3ecb ProSAT]</span></td></tr>
	</table>		</table>
	== Function ==		== Function ==
	[[~~http~~://www.uniprot.org/uniprot/HA12_MOUSE HA12_MOUSE]] Involved in the presentation of foreign antigens to the immune system. [[~~http~~://www.uniprot.org/uniprot/ENV_HV1MF ENV_HV1MF]] The surface protein gp120 (SU) attaches the virus to the host lymphoid cell by binding to the primary receptor CD4. This interaction induces a structural rearrangement creating a high affinity binding site for a chemokine coreceptor like CXCR4 and/or CCR5. This peculiar 2 stage receptor-interaction strategy allows gp120 to maintain the highly conserved coreceptor-binding site in a cryptic conformation, protected from neutralizing antibodies. Since CD4 also displays a binding site for the disulfide-isomerase P4HB/PDI, a P4HB/PDI-CD4-CXCR4-gp120 complex may form. In that complex, P4HB/PDI could reach and reduce gp120 disulfide bonds, causing major conformational changes in gp120. TXN, another PDI family member could also be involved in disulfide rearrangements in Env during fusion. These changes are transmitted to the transmembrane protein gp41 and are thought to activate its fusogenic potential by unmasking its fusion peptide. Surface protein gp120 (SU) may target the virus to gut-associated lymphoid tissue (GALT) by binding host ITGA4/ITGB7 (alpha-4/beta-7 integrins), a complex that mediates T-cell migration to the GALT. Interaction between gp120 and ITGA4/ITGB7 would allow the virus to enter GALT early in the infection, infecting and killing most of GALT's resting CD4+ T-cells. This T-cell depletion is believed to be the major insult to the host immune system leading to AIDS (By similarity). The surface protein gp120 is a ligand for CD209/DC-SIGN and CLEC4M/DC-SIGNR, which are respectively found on dendritic cells (DCs), and on endothelial cells of liver sinusoids and lymph node sinuses. These interactions allow capture of viral particles at mucosal surfaces by these cells and subsequent transmission to permissive cells. DCs are professional antigen presenting cells, critical for host immunity by inducing specific immune responses against a broad variety of pathogens. They act as sentinels in various tissues where they take up antigen, process it, and present it to T-cells following migration to lymphoid organs. HIV subverts the migration properties of dendritic cells to gain access to CD4+ T-cells in lymph nodes. Virus transmission to permissive T-cells occurs either in trans (without DCs infection, through viral capture and transmission), or in cis (following DCs productive infection, through the usual CD4-gp120 interaction), thereby inducing a robust infection. In trans infection, bound virions remain infectious over days and it is proposed that they are not degraded, but protected in non-lysosomal acidic organelles within the DCs close to the cell membrane thus contributing to the viral infectious potential during DCs' migration from the periphery to the lymphoid tissues. On arrival at lymphoid tissues, intact virions recycle back to DCs' cell surface allowing virus transmission to CD4+ T-cells. Virion capture also seems to lead to MHC-II-restricted viral antigen presentation, and probably to the activation of HIV-specific CD4+ cells (By similarity). The transmembrane protein gp41 (TM) acts as a class I viral fusion protein. Under the current model, the protein has at least 3 conformational states: pre-fusion native state, pre-hairpin intermediate state, and post-fusion hairpin state. During fusion of viral and target intracellular membranes, the coiled coil regions (heptad repeats) assume a trimer-of-hairpins structure, positioning the fusion peptide in close proximity to the C-terminal region of the ectodomain. The formation of this structure appears to drive apposition and subsequent fusion of viral and target cell membranes. Complete fusion occurs in host cell endosomes and is dynamin-dependent, however some lipid transfer might occur at the plasma membrane. The virus undergoes clathrin-dependent internalization long before endosomal fusion, thus minimizing the surface exposure of conserved viral epitopes during fusion and reducing the efficacy of inhibitors targeting these epitopes. Membranes fusion leads to delivery of the nucleocapsid into the cytoplasm (By similarity). The envelope glyprotein gp160 precursor down-modulates cell surface CD4 antigen by interacting with it in the endoplasmic reticulum and blocking its transport to the cell surface (By similarity). The gp120-gp41 heterodimer seems to contribute to T-cell depletion during HIV-1 infection. The envelope glycoproteins expressed on the surface of infected cells induce apoptosis through an interaction with uninfected cells expressing the receptor (CD4) and the coreceptors CXCR4 or CCR5. This type of bystander killing may be obtained by at least three distinct mechanisms. First, the interaction between the 2 cells can induce cellular fusion followed by nuclear fusion within the syncytium. Syncytia are condemned to die from apoptosis. Second, the 2 interacting cells may not fuse entirely and simply exchange plasma membrane lipids, after a sort of hemifusion process, followed by rapid death. Third, it is possible that virus-infected cells, on the point of undergoing apoptosis, fuse with CD4-expressing cells, in which case apoptosis is rapidly transmitted from one cell to the other and thus occurs in a sort of contagious fashion (By similarity). The gp120-gp41 heterodimer allows rapid transcytosis of the virus through CD4 negative cells such as simple epithelial monolayers of the intestinal, rectal and endocervical epithelial barriers. Both gp120 and gp41 specifically recognize glycosphingolipids galactosyl-ceramide (GalCer) or 3' sulfo-galactosyl-ceramide (GalS) present in the lipid rafts structures of epithelial cells. Binding to these alternative receptors allows the rapid transcytosis of the virus through the epithelial cells. This transcytotic vesicle-mediated transport of virions from the apical side to the basolateral side of the epithelial cells does not involve infection of the cells themselves (By similarity). [[~~http~~://www.uniprot.org/uniprot/B2MG_MOUSE B2MG_MOUSE]] Component of the class I major histocompatibility complex (MHC). Involved in the presentation of peptide antigens to the immune system.		[[https://www.uniprot.org/uniprot/HA12_MOUSE HA12_MOUSE]] Involved in the presentation of foreign antigens to the immune system. [[https://www.uniprot.org/uniprot/ENV_HV1MF ENV_HV1MF]] The surface protein gp120 (SU) attaches the virus to the host lymphoid cell by binding to the primary receptor CD4. This interaction induces a structural rearrangement creating a high affinity binding site for a chemokine coreceptor like CXCR4 and/or CCR5. This peculiar 2 stage receptor-interaction strategy allows gp120 to maintain the highly conserved coreceptor-binding site in a cryptic conformation, protected from neutralizing antibodies. Since CD4 also displays a binding site for the disulfide-isomerase P4HB/PDI, a P4HB/PDI-CD4-CXCR4-gp120 complex may form. In that complex, P4HB/PDI could reach and reduce gp120 disulfide bonds, causing major conformational changes in gp120. TXN, another PDI family member could also be involved in disulfide rearrangements in Env during fusion. These changes are transmitted to the transmembrane protein gp41 and are thought to activate its fusogenic potential by unmasking its fusion peptide. Surface protein gp120 (SU) may target the virus to gut-associated lymphoid tissue (GALT) by binding host ITGA4/ITGB7 (alpha-4/beta-7 integrins), a complex that mediates T-cell migration to the GALT. Interaction between gp120 and ITGA4/ITGB7 would allow the virus to enter GALT early in the infection, infecting and killing most of GALT's resting CD4+ T-cells. This T-cell depletion is believed to be the major insult to the host immune system leading to AIDS (By similarity). The surface protein gp120 is a ligand for CD209/DC-SIGN and CLEC4M/DC-SIGNR, which are respectively found on dendritic cells (DCs), and on endothelial cells of liver sinusoids and lymph node sinuses. These interactions allow capture of viral particles at mucosal surfaces by these cells and subsequent transmission to permissive cells. DCs are professional antigen presenting cells, critical for host immunity by inducing specific immune responses against a broad variety of pathogens. They act as sentinels in various tissues where they take up antigen, process it, and present it to T-cells following migration to lymphoid organs. HIV subverts the migration properties of dendritic cells to gain access to CD4+ T-cells in lymph nodes. Virus transmission to permissive T-cells occurs either in trans (without DCs infection, through viral capture and transmission), or in cis (following DCs productive infection, through the usual CD4-gp120 interaction), thereby inducing a robust infection. In trans infection, bound virions remain infectious over days and it is proposed that they are not degraded, but protected in non-lysosomal acidic organelles within the DCs close to the cell membrane thus contributing to the viral infectious potential during DCs' migration from the periphery to the lymphoid tissues. On arrival at lymphoid tissues, intact virions recycle back to DCs' cell surface allowing virus transmission to CD4+ T-cells. Virion capture also seems to lead to MHC-II-restricted viral antigen presentation, and probably to the activation of HIV-specific CD4+ cells (By similarity). The transmembrane protein gp41 (TM) acts as a class I viral fusion protein. Under the current model, the protein has at least 3 conformational states: pre-fusion native state, pre-hairpin intermediate state, and post-fusion hairpin state. During fusion of viral and target intracellular membranes, the coiled coil regions (heptad repeats) assume a trimer-of-hairpins structure, positioning the fusion peptide in close proximity to the C-terminal region of the ectodomain. The formation of this structure appears to drive apposition and subsequent fusion of viral and target cell membranes. Complete fusion occurs in host cell endosomes and is dynamin-dependent, however some lipid transfer might occur at the plasma membrane. The virus undergoes clathrin-dependent internalization long before endosomal fusion, thus minimizing the surface exposure of conserved viral epitopes during fusion and reducing the efficacy of inhibitors targeting these epitopes. Membranes fusion leads to delivery of the nucleocapsid into the cytoplasm (By similarity). The envelope glyprotein gp160 precursor down-modulates cell surface CD4 antigen by interacting with it in the endoplasmic reticulum and blocking its transport to the cell surface (By similarity). The gp120-gp41 heterodimer seems to contribute to T-cell depletion during HIV-1 infection. The envelope glycoproteins expressed on the surface of infected cells induce apoptosis through an interaction with uninfected cells expressing the receptor (CD4) and the coreceptors CXCR4 or CCR5. This type of bystander killing may be obtained by at least three distinct mechanisms. First, the interaction between the 2 cells can induce cellular fusion followed by nuclear fusion within the syncytium. Syncytia are condemned to die from apoptosis. Second, the 2 interacting cells may not fuse entirely and simply exchange plasma membrane lipids, after a sort of hemifusion process, followed by rapid death. Third, it is possible that virus-infected cells, on the point of undergoing apoptosis, fuse with CD4-expressing cells, in which case apoptosis is rapidly transmitted from one cell to the other and thus occurs in a sort of contagious fashion (By similarity). The gp120-gp41 heterodimer allows rapid transcytosis of the virus through CD4 negative cells such as simple epithelial monolayers of the intestinal, rectal and endocervical epithelial barriers. Both gp120 and gp41 specifically recognize glycosphingolipids galactosyl-ceramide (GalCer) or 3' sulfo-galactosyl-ceramide (GalS) present in the lipid rafts structures of epithelial cells. Binding to these alternative receptors allows the rapid transcytosis of the virus through the epithelial cells. This transcytotic vesicle-mediated transport of virions from the apical side to the basolateral side of the epithelial cells does not involve infection of the cells themselves (By similarity). [[https://www.uniprot.org/uniprot/B2MG_MOUSE B2MG_MOUSE]] Component of the class I major histocompatibility complex (MHC). Involved in the presentation of peptide antigens to the immune system.
	== Evolutionary Conservation ==		== Evolutionary Conservation ==
	[[Image:Consurf_key_small.gif\|200px\|right]]		[[Image:Consurf_key_small.gif\|200px\|right]]
Line 32:		Line 32:

	==See Also==		==See Also==
	*[[Beta-2 microglobulin\|Beta-2 microglobulin]]		*[[Beta-2 microglobulin 3D structures\|Beta-2 microglobulin 3D structures]]
	*[[~~Major histocompatibility complex~~\|~~Major histocompatibility complex~~]]		*[[MHC 3D structures\|MHC 3D structures]]
	== References ==		== References ==
	<references/>		<references/>
	__TOC__		__TOC__
	</StructureSection>		</StructureSection>
			[[Category: Large Structures]]
	[[Category: Lk3 transgenic mice]]		[[Category: Lk3 transgenic mice]]
	[[Category: Margulies, D H]]		[[Category: Margulies, D H]]

OCA at 21:50, 2 December 2018

2018-12-02T21:50:11Z

← Older revision		Revision as of 21:50, 2 December 2018
Line 1:		Line 1:

	==Crystal structure of mouse H-2Dd in complex with peptide P18-I10 derived from human immunodeficiency virus envelope glycoprotein 120==		==Crystal structure of mouse H-2Dd in complex with peptide P18-I10 derived from human immunodeficiency virus envelope glycoprotein 120==
	<StructureSection load='3ecb' size='340' side='right' caption='[[3ecb]], [[Resolution\|resolution]] 1.70Å' scene=''>		<StructureSection load='3ecb' size='340' side='right' caption='[[3ecb]], [[Resolution\|resolution]] 1.70Å' scene=''>
Line 6:		Line 7:
	<tr id='related'><td class="sblockLbl"><b>[[Related_structure\|Related:]]</b></td><td class="sblockDat">[[3dmm\|3dmm]]</td></tr>		<tr id='related'><td class="sblockLbl"><b>[[Related_structure\|Related:]]</b></td><td class="sblockDat">[[3dmm\|3dmm]]</td></tr>
	<tr id='gene'><td class="sblockLbl"><b>[[Gene\|Gene:]]</b></td><td class="sblockDat">H2-D1 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=10090 LK3 transgenic mice]), B2m, RP23-34E24.5-001 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=10090 LK3 transgenic mice])</td></tr>		<tr id='gene'><td class="sblockLbl"><b>[[Gene\|Gene:]]</b></td><td class="sblockDat">H2-D1 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=10090 LK3 transgenic mice]), B2m, RP23-34E24.5-001 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=10090 LK3 transgenic mice])</td></tr>
	<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3ecb FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3ecb OCA], [http://pdbe.org/3ecb PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=3ecb RCSB], [http://www.ebi.ac.uk/pdbsum/3ecb PDBsum]</span></td></tr>		<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3ecb FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3ecb OCA], [http://pdbe.org/3ecb PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=3ecb RCSB], [http://www.ebi.ac.uk/pdbsum/3ecb PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=3ecb ProSAT]</span></td></tr>
	</table>		</table>
	== Function ==		== Function ==
Line 14:		Line 15:
	Check<jmol>		Check<jmol>
	<jmolCheckbox>		<jmolCheckbox>
	<scriptWhenChecked>select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/ec/3ecb_consurf.spt"</scriptWhenChecked>		<scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/ec/3ecb_consurf.spt"</scriptWhenChecked>
	<scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>		<scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
	<text>to colour the structure by Evolutionary Conservation</text>		<text>to colour the structure by Evolutionary Conservation</text>
Line 46:		Line 47:
	[[Category: Class i major histompatibility complex]]		[[Category: Class i major histompatibility complex]]
	[[Category: Cleavage on pair of basic residue]]		[[Category: Cleavage on pair of basic residue]]
			[[Category: Coiled coil]]
	[[Category: Envelope protein]]		[[Category: Envelope protein]]
	[[Category: Fusion protein]]		[[Category: Fusion protein]]

OCA at 17:00, 7 February 2016

2016-02-07T17:00:51Z

← Older revision		Revision as of 17:00, 7 February 2016
Line 2:		Line 2:
	<StructureSection load='3ecb' size='340' side='right' caption='[[3ecb]], [[Resolution\|resolution]] 1.70Å' scene=''>		<StructureSection load='3ecb' size='340' side='right' caption='[[3ecb]], [[Resolution\|resolution]] 1.70Å' scene=''>
	== Structural highlights ==		== Structural highlights ==
	<table><tr><td colspan='2'>[[3ecb]] is a 3 chain structure with sequence from [http://en.wikipedia.org/wiki/~~Mus_musculus Mus musculus~~]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3ECB OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3ECB FirstGlance]. <br>		<table><tr><td colspan='2'>[[3ecb]] is a 3 chain structure with sequence from [http://en.wikipedia.org/wiki/Lk3_transgenic_mice Lk3 transgenic mice]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3ECB OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3ECB FirstGlance]. <br>
	</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand\|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=EDO:1,2-ETHANEDIOL'>EDO</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene></td></tr>		</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand\|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=EDO:1,2-ETHANEDIOL'>EDO</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene></td></tr>
	<tr id='related'><td class="sblockLbl"><b>[[Related_structure\|Related:]]</b></td><td class="sblockDat">[[3dmm\|3dmm]]</td></tr>		<tr id='related'><td class="sblockLbl"><b>[[Related_structure\|Related:]]</b></td><td class="sblockDat">[[3dmm\|3dmm]]</td></tr>
	<tr id='gene'><td class="sblockLbl"><b>[[Gene\|Gene:]]</b></td><td class="sblockDat">H2-D1 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=10090 ~~Mus musculus~~]), B2m, RP23-34E24.5-001 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=10090 ~~Mus musculus~~])</td></tr>		<tr id='gene'><td class="sblockLbl"><b>[[Gene\|Gene:]]</b></td><td class="sblockDat">H2-D1 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=10090 LK3 transgenic mice]), B2m, RP23-34E24.5-001 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=10090 LK3 transgenic mice])</td></tr>
	<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3ecb FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3ecb OCA], [http://www.rcsb.org/pdb/explore.do?structureId=3ecb RCSB], [http://www.ebi.ac.uk/pdbsum/3ecb PDBsum]</span></td></tr>		<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3ecb FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3ecb OCA], [http://pdbe.org/3ecb PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=3ecb RCSB], [http://www.ebi.ac.uk/pdbsum/3ecb PDBsum]</span></td></tr>
	</table>		</table>
	== Function ==		== Function ==
	[[http://www.uniprot.org/uniprot/HA12_MOUSE HA12_MOUSE]] Involved in the presentation of foreign antigens to the immune system. [[http://www.uniprot.org/uniprot/ENV_HV1MF ENV_HV1MF]] The surface protein gp120 (SU) attaches the virus to the host lymphoid cell by binding to the primary receptor CD4. This interaction induces a structural rearrangement creating a high affinity binding site for a chemokine coreceptor like CXCR4 and/or CCR5. This peculiar 2 stage receptor-interaction strategy allows gp120 to maintain the highly conserved coreceptor-binding site in a cryptic conformation, protected from neutralizing antibodies. Since CD4 also displays a binding site for the disulfide-isomerase P4HB/PDI, a P4HB/PDI-CD4-CXCR4-gp120 complex may form. In that complex, P4HB/PDI could reach and reduce gp120 disulfide bonds, causing major conformational changes in gp120. TXN, another PDI family member could also be involved in disulfide rearrangements in Env during fusion. These changes are transmitted to the transmembrane protein gp41 and are thought to activate its fusogenic potential by unmasking its fusion peptide. Surface protein gp120 (SU) may target the virus to gut-associated lymphoid tissue (GALT) by binding host ITGA4/ITGB7 (alpha-4/beta-7 integrins), a complex that mediates T-cell migration to the GALT. Interaction between gp120 and ITGA4/ITGB7 would allow the virus to enter GALT early in the infection, infecting and killing most of GALT's resting CD4+ T-cells. This T-cell depletion is believed to be the major insult to the host immune system leading to AIDS (By similarity). The surface protein gp120 is a ligand for CD209/DC-SIGN and CLEC4M/DC-SIGNR, which are respectively found on dendritic cells (DCs), and on endothelial cells of liver sinusoids and lymph node sinuses. These interactions allow capture of viral particles at mucosal surfaces by these cells and subsequent transmission to permissive cells. DCs are professional antigen presenting cells, critical for host immunity by inducing specific immune responses against a broad variety of pathogens. They act as sentinels in various tissues where they take up antigen, process it, and present it to T-cells following migration to lymphoid organs. HIV subverts the migration properties of dendritic cells to gain access to CD4+ T-cells in lymph nodes. Virus transmission to permissive T-cells occurs either in trans (without DCs infection, through viral capture and transmission), or in cis (following DCs productive infection, through the usual CD4-gp120 interaction), thereby inducing a robust infection. In trans infection, bound virions remain infectious over days and it is proposed that they are not degraded, but protected in non-lysosomal acidic organelles within the DCs close to the cell membrane thus contributing to the viral infectious potential during DCs' migration from the periphery to the lymphoid tissues. On arrival at lymphoid tissues, intact virions recycle back to DCs' cell surface allowing virus transmission to CD4+ T-cells. Virion capture also seems to lead to MHC-II-restricted viral antigen presentation, and probably to the activation of HIV-specific CD4+ cells (By similarity). The transmembrane protein gp41 (TM) acts as a class I viral fusion protein. Under the current model, the protein has at least 3 conformational states: pre-fusion native state, pre-hairpin intermediate state, and post-fusion hairpin state. During fusion of viral and target intracellular membranes, the coiled coil regions (heptad repeats) assume a trimer-of-hairpins structure, positioning the fusion peptide in close proximity to the C-terminal region of the ectodomain. The formation of this structure appears to drive apposition and subsequent fusion of viral and target cell membranes. Complete fusion occurs in host cell endosomes and is dynamin-dependent, however some lipid transfer might occur at the plasma membrane. The virus undergoes clathrin-dependent internalization long before endosomal fusion, thus minimizing the surface exposure of conserved viral epitopes during fusion and reducing the efficacy of inhibitors targeting these epitopes. Membranes fusion leads to delivery of the nucleocapsid into the cytoplasm (By similarity). The envelope glyprotein gp160 precursor down-modulates cell surface CD4 antigen by interacting with it in the endoplasmic reticulum and blocking its transport to the cell surface (By similarity). The gp120-gp41 heterodimer seems to contribute to T-cell depletion during HIV-1 infection. The envelope glycoproteins expressed on the surface of infected cells induce apoptosis through an interaction with uninfected cells expressing the receptor (CD4) and the coreceptors CXCR4 or CCR5. This type of bystander killing may be obtained by at least three distinct mechanisms. First, the interaction between the 2 cells can induce cellular fusion followed by nuclear fusion within the syncytium. Syncytia are condemned to die from apoptosis. Second, the 2 interacting cells may not fuse entirely and simply exchange plasma membrane lipids, after a sort of hemifusion process, followed by rapid death. Third, it is possible that virus-infected cells, on the point of undergoing apoptosis, fuse with CD4-expressing cells, in which case apoptosis is rapidly transmitted from one cell to the other and thus occurs in a sort of contagious fashion (By similarity). The gp120-gp41 heterodimer allows rapid transcytosis of the virus through CD4 negative cells such as simple epithelial monolayers of the intestinal, rectal and endocervical epithelial barriers. Both gp120 and gp41 specifically recognize glycosphingolipids galactosyl-ceramide (GalCer) or 3' sulfo-galactosyl-ceramide (GalS) present in the lipid rafts structures of epithelial cells. Binding to these alternative receptors allows the rapid transcytosis of the virus through the epithelial cells. This transcytotic vesicle-mediated transport of virions from the apical side to the basolateral side of the epithelial cells does not involve infection of the cells themselves (By similarity). [[http://www.uniprot.org/uniprot/~~Q91XJ8_MOUSE Q91XJ8_MOUSE~~]] Component of the class I major histocompatibility complex (MHC). Involved in the presentation of peptide antigens to the immune system.		[[http://www.uniprot.org/uniprot/HA12_MOUSE HA12_MOUSE]] Involved in the presentation of foreign antigens to the immune system. [[http://www.uniprot.org/uniprot/ENV_HV1MF ENV_HV1MF]] The surface protein gp120 (SU) attaches the virus to the host lymphoid cell by binding to the primary receptor CD4. This interaction induces a structural rearrangement creating a high affinity binding site for a chemokine coreceptor like CXCR4 and/or CCR5. This peculiar 2 stage receptor-interaction strategy allows gp120 to maintain the highly conserved coreceptor-binding site in a cryptic conformation, protected from neutralizing antibodies. Since CD4 also displays a binding site for the disulfide-isomerase P4HB/PDI, a P4HB/PDI-CD4-CXCR4-gp120 complex may form. In that complex, P4HB/PDI could reach and reduce gp120 disulfide bonds, causing major conformational changes in gp120. TXN, another PDI family member could also be involved in disulfide rearrangements in Env during fusion. These changes are transmitted to the transmembrane protein gp41 and are thought to activate its fusogenic potential by unmasking its fusion peptide. Surface protein gp120 (SU) may target the virus to gut-associated lymphoid tissue (GALT) by binding host ITGA4/ITGB7 (alpha-4/beta-7 integrins), a complex that mediates T-cell migration to the GALT. Interaction between gp120 and ITGA4/ITGB7 would allow the virus to enter GALT early in the infection, infecting and killing most of GALT's resting CD4+ T-cells. This T-cell depletion is believed to be the major insult to the host immune system leading to AIDS (By similarity). The surface protein gp120 is a ligand for CD209/DC-SIGN and CLEC4M/DC-SIGNR, which are respectively found on dendritic cells (DCs), and on endothelial cells of liver sinusoids and lymph node sinuses. These interactions allow capture of viral particles at mucosal surfaces by these cells and subsequent transmission to permissive cells. DCs are professional antigen presenting cells, critical for host immunity by inducing specific immune responses against a broad variety of pathogens. They act as sentinels in various tissues where they take up antigen, process it, and present it to T-cells following migration to lymphoid organs. HIV subverts the migration properties of dendritic cells to gain access to CD4+ T-cells in lymph nodes. Virus transmission to permissive T-cells occurs either in trans (without DCs infection, through viral capture and transmission), or in cis (following DCs productive infection, through the usual CD4-gp120 interaction), thereby inducing a robust infection. In trans infection, bound virions remain infectious over days and it is proposed that they are not degraded, but protected in non-lysosomal acidic organelles within the DCs close to the cell membrane thus contributing to the viral infectious potential during DCs' migration from the periphery to the lymphoid tissues. On arrival at lymphoid tissues, intact virions recycle back to DCs' cell surface allowing virus transmission to CD4+ T-cells. Virion capture also seems to lead to MHC-II-restricted viral antigen presentation, and probably to the activation of HIV-specific CD4+ cells (By similarity). The transmembrane protein gp41 (TM) acts as a class I viral fusion protein. Under the current model, the protein has at least 3 conformational states: pre-fusion native state, pre-hairpin intermediate state, and post-fusion hairpin state. During fusion of viral and target intracellular membranes, the coiled coil regions (heptad repeats) assume a trimer-of-hairpins structure, positioning the fusion peptide in close proximity to the C-terminal region of the ectodomain. The formation of this structure appears to drive apposition and subsequent fusion of viral and target cell membranes. Complete fusion occurs in host cell endosomes and is dynamin-dependent, however some lipid transfer might occur at the plasma membrane. The virus undergoes clathrin-dependent internalization long before endosomal fusion, thus minimizing the surface exposure of conserved viral epitopes during fusion and reducing the efficacy of inhibitors targeting these epitopes. Membranes fusion leads to delivery of the nucleocapsid into the cytoplasm (By similarity). The envelope glyprotein gp160 precursor down-modulates cell surface CD4 antigen by interacting with it in the endoplasmic reticulum and blocking its transport to the cell surface (By similarity). The gp120-gp41 heterodimer seems to contribute to T-cell depletion during HIV-1 infection. The envelope glycoproteins expressed on the surface of infected cells induce apoptosis through an interaction with uninfected cells expressing the receptor (CD4) and the coreceptors CXCR4 or CCR5. This type of bystander killing may be obtained by at least three distinct mechanisms. First, the interaction between the 2 cells can induce cellular fusion followed by nuclear fusion within the syncytium. Syncytia are condemned to die from apoptosis. Second, the 2 interacting cells may not fuse entirely and simply exchange plasma membrane lipids, after a sort of hemifusion process, followed by rapid death. Third, it is possible that virus-infected cells, on the point of undergoing apoptosis, fuse with CD4-expressing cells, in which case apoptosis is rapidly transmitted from one cell to the other and thus occurs in a sort of contagious fashion (By similarity). The gp120-gp41 heterodimer allows rapid transcytosis of the virus through CD4 negative cells such as simple epithelial monolayers of the intestinal, rectal and endocervical epithelial barriers. Both gp120 and gp41 specifically recognize glycosphingolipids galactosyl-ceramide (GalCer) or 3' sulfo-galactosyl-ceramide (GalS) present in the lipid rafts structures of epithelial cells. Binding to these alternative receptors allows the rapid transcytosis of the virus through the epithelial cells. This transcytotic vesicle-mediated transport of virions from the apical side to the basolateral side of the epithelial cells does not involve infection of the cells themselves (By similarity). [[http://www.uniprot.org/uniprot/B2MG_MOUSE B2MG_MOUSE]] Component of the class I major histocompatibility complex (MHC). Involved in the presentation of peptide antigens to the immune system.
	== Evolutionary Conservation ==		== Evolutionary Conservation ==
	[[Image:Consurf_key_small.gif\|200px\|right]]		[[Image:Consurf_key_small.gif\|200px\|right]]
Line 18:		Line 18:
	<text>to colour the structure by Evolutionary Conservation</text>		<text>to colour the structure by Evolutionary Conservation</text>
	</jmolCheckbox>		</jmolCheckbox>
	</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary\|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/~~chain_selection~~.php?pdb_ID=~~2ata~~ ConSurf].		</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary\|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=3ecb ConSurf].
	<div style="clear:both"></div>		<div style="clear:both"></div>
	<div style="background-color:#fffaf0;">		<div style="background-color:#fffaf0;">
Line 28:		Line 28:
	From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br>		From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br>
	</div>		</div>
			<div class="pdbe-citations 3ecb" style="background-color:#fffaf0;"></div>

	==See Also==		==See Also==
Line 36:		Line 37:
	__TOC__		__TOC__
	</StructureSection>		</StructureSection>
	[[Category: ~~Mus musculus~~]]		[[Category: Lk3 transgenic mice]]
	[[Category: Margulies, D H]]		[[Category: Margulies, D H]]
	[[Category: Natarajan, K]]		[[Category: Natarajan, K]]

OCA at 16:53, 24 December 2014

2014-12-24T16:53:21Z

← Older revision		Revision as of 16:53, 24 December 2014
Line 3:		Line 3:
	== Structural highlights ==		== Structural highlights ==
	<table><tr><td colspan='2'>[[3ecb]] is a 3 chain structure with sequence from [http://en.wikipedia.org/wiki/Mus_musculus Mus musculus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3ECB OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3ECB FirstGlance]. <br>		<table><tr><td colspan='2'>[[3ecb]] is a 3 chain structure with sequence from [http://en.wikipedia.org/wiki/Mus_musculus Mus musculus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3ECB OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3ECB FirstGlance]. <br>
	</td></tr><tr><td class="sblockLbl"><b>[[Ligand\|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=EDO:1,2-ETHANEDIOL'>EDO</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene><br>		</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand\|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=EDO:1,2-ETHANEDIOL'>EDO</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene></td></tr>
	<tr><td class="sblockLbl"><b>[[Related_structure\|Related:]]</b></td><td class="sblockDat">[[3dmm\|3dmm]]</td></tr>		<tr id='related'><td class="sblockLbl"><b>[[Related_structure\|Related:]]</b></td><td class="sblockDat">[[3dmm\|3dmm]]</td></tr>
	<tr><td class="sblockLbl"><b>[[Gene\|Gene:]]</b></td><td class="sblockDat">H2-D1 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=10090 Mus musculus]), B2m, RP23-34E24.5-001 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=10090 Mus musculus])</td></tr>		<tr id='gene'><td class="sblockLbl"><b>[[Gene\|Gene:]]</b></td><td class="sblockDat">H2-D1 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=10090 Mus musculus]), B2m, RP23-34E24.5-001 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=10090 Mus musculus])</td></tr>
	<tr><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3ecb FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3ecb OCA], [http://www.rcsb.org/pdb/explore.do?structureId=3ecb RCSB], [http://www.ebi.ac.uk/pdbsum/3ecb PDBsum]</span></td></tr>		<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3ecb FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3ecb OCA], [http://www.rcsb.org/pdb/explore.do?structureId=3ecb RCSB], [http://www.ebi.ac.uk/pdbsum/3ecb PDBsum]</span></td></tr>
	<table>		</table>
			== Function ==
			[[http://www.uniprot.org/uniprot/HA12_MOUSE HA12_MOUSE]] Involved in the presentation of foreign antigens to the immune system. [[http://www.uniprot.org/uniprot/ENV_HV1MF ENV_HV1MF]] The surface protein gp120 (SU) attaches the virus to the host lymphoid cell by binding to the primary receptor CD4. This interaction induces a structural rearrangement creating a high affinity binding site for a chemokine coreceptor like CXCR4 and/or CCR5. This peculiar 2 stage receptor-interaction strategy allows gp120 to maintain the highly conserved coreceptor-binding site in a cryptic conformation, protected from neutralizing antibodies. Since CD4 also displays a binding site for the disulfide-isomerase P4HB/PDI, a P4HB/PDI-CD4-CXCR4-gp120 complex may form. In that complex, P4HB/PDI could reach and reduce gp120 disulfide bonds, causing major conformational changes in gp120. TXN, another PDI family member could also be involved in disulfide rearrangements in Env during fusion. These changes are transmitted to the transmembrane protein gp41 and are thought to activate its fusogenic potential by unmasking its fusion peptide. Surface protein gp120 (SU) may target the virus to gut-associated lymphoid tissue (GALT) by binding host ITGA4/ITGB7 (alpha-4/beta-7 integrins), a complex that mediates T-cell migration to the GALT. Interaction between gp120 and ITGA4/ITGB7 would allow the virus to enter GALT early in the infection, infecting and killing most of GALT's resting CD4+ T-cells. This T-cell depletion is believed to be the major insult to the host immune system leading to AIDS (By similarity). The surface protein gp120 is a ligand for CD209/DC-SIGN and CLEC4M/DC-SIGNR, which are respectively found on dendritic cells (DCs), and on endothelial cells of liver sinusoids and lymph node sinuses. These interactions allow capture of viral particles at mucosal surfaces by these cells and subsequent transmission to permissive cells. DCs are professional antigen presenting cells, critical for host immunity by inducing specific immune responses against a broad variety of pathogens. They act as sentinels in various tissues where they take up antigen, process it, and present it to T-cells following migration to lymphoid organs. HIV subverts the migration properties of dendritic cells to gain access to CD4+ T-cells in lymph nodes. Virus transmission to permissive T-cells occurs either in trans (without DCs infection, through viral capture and transmission), or in cis (following DCs productive infection, through the usual CD4-gp120 interaction), thereby inducing a robust infection. In trans infection, bound virions remain infectious over days and it is proposed that they are not degraded, but protected in non-lysosomal acidic organelles within the DCs close to the cell membrane thus contributing to the viral infectious potential during DCs' migration from the periphery to the lymphoid tissues. On arrival at lymphoid tissues, intact virions recycle back to DCs' cell surface allowing virus transmission to CD4+ T-cells. Virion capture also seems to lead to MHC-II-restricted viral antigen presentation, and probably to the activation of HIV-specific CD4+ cells (By similarity). The transmembrane protein gp41 (TM) acts as a class I viral fusion protein. Under the current model, the protein has at least 3 conformational states: pre-fusion native state, pre-hairpin intermediate state, and post-fusion hairpin state. During fusion of viral and target intracellular membranes, the coiled coil regions (heptad repeats) assume a trimer-of-hairpins structure, positioning the fusion peptide in close proximity to the C-terminal region of the ectodomain. The formation of this structure appears to drive apposition and subsequent fusion of viral and target cell membranes. Complete fusion occurs in host cell endosomes and is dynamin-dependent, however some lipid transfer might occur at the plasma membrane. The virus undergoes clathrin-dependent internalization long before endosomal fusion, thus minimizing the surface exposure of conserved viral epitopes during fusion and reducing the efficacy of inhibitors targeting these epitopes. Membranes fusion leads to delivery of the nucleocapsid into the cytoplasm (By similarity). The envelope glyprotein gp160 precursor down-modulates cell surface CD4 antigen by interacting with it in the endoplasmic reticulum and blocking its transport to the cell surface (By similarity). The gp120-gp41 heterodimer seems to contribute to T-cell depletion during HIV-1 infection. The envelope glycoproteins expressed on the surface of infected cells induce apoptosis through an interaction with uninfected cells expressing the receptor (CD4) and the coreceptors CXCR4 or CCR5. This type of bystander killing may be obtained by at least three distinct mechanisms. First, the interaction between the 2 cells can induce cellular fusion followed by nuclear fusion within the syncytium. Syncytia are condemned to die from apoptosis. Second, the 2 interacting cells may not fuse entirely and simply exchange plasma membrane lipids, after a sort of hemifusion process, followed by rapid death. Third, it is possible that virus-infected cells, on the point of undergoing apoptosis, fuse with CD4-expressing cells, in which case apoptosis is rapidly transmitted from one cell to the other and thus occurs in a sort of contagious fashion (By similarity). The gp120-gp41 heterodimer allows rapid transcytosis of the virus through CD4 negative cells such as simple epithelial monolayers of the intestinal, rectal and endocervical epithelial barriers. Both gp120 and gp41 specifically recognize glycosphingolipids galactosyl-ceramide (GalCer) or 3' sulfo-galactosyl-ceramide (GalS) present in the lipid rafts structures of epithelial cells. Binding to these alternative receptors allows the rapid transcytosis of the virus through the epithelial cells. This transcytotic vesicle-mediated transport of virions from the apical side to the basolateral side of the epithelial cells does not involve infection of the cells themselves (By similarity). [[http://www.uniprot.org/uniprot/Q91XJ8_MOUSE Q91XJ8_MOUSE]] Component of the class I major histocompatibility complex (MHC). Involved in the presentation of peptide antigens to the immune system.
	== Evolutionary Conservation ==		== Evolutionary Conservation ==
	[[Image:Consurf_key_small.gif\|200px\|right]]		[[Image:Consurf_key_small.gif\|200px\|right]]
Line 35:		Line 37:
	</StructureSection>		</StructureSection>
	[[Category: Mus musculus]]		[[Category: Mus musculus]]
	[[Category: Margulies, D H.]]		[[Category: Margulies, D H]]
	[[Category: Natarajan, K.]]		[[Category: Natarajan, K]]
	[[Category: Wang, R.]]		[[Category: Wang, R]]
	[[Category: Aid]]		[[Category: Aid]]
	[[Category: Apoptosis]]		[[Category: Apoptosis]]

OCA at 13:12, 29 September 2014

2014-09-29T13:12:28Z

← Older revision		Revision as of 13:12, 29 September 2014
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	[[Image:~~3ecb~~.~~png~~\|~~left~~\|~~200px~~]]		==Crystal structure of mouse H-2Dd in complex with peptide P18-I10 derived from human immunodeficiency virus envelope glycoprotein 120==
			<StructureSection load='3ecb' size='340' side='right' caption='[[3ecb]], [[Resolution\|resolution]] 1.70Å' scene=''>
			== Structural highlights ==
			<table><tr><td colspan='2'>[[3ecb]] is a 3 chain structure with sequence from [http://en.wikipedia.org/wiki/Mus_musculus Mus musculus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3ECB OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3ECB FirstGlance]. <br>
			</td></tr><tr><td class="sblockLbl"><b>[[Ligand\|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=EDO:1,2-ETHANEDIOL'>EDO</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene><br>
			<tr><td class="sblockLbl"><b>[[Related_structure\|Related:]]</b></td><td class="sblockDat">[[3dmm\|3dmm]]</td></tr>
			<tr><td class="sblockLbl"><b>[[Gene\|Gene:]]</b></td><td class="sblockDat">H2-D1 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=10090 Mus musculus]), B2m, RP23-34E24.5-001 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=10090 Mus musculus])</td></tr>
			<tr><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3ecb FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3ecb OCA], [http://www.rcsb.org/pdb/explore.do?structureId=3ecb RCSB], [http://www.ebi.ac.uk/pdbsum/3ecb PDBsum]</span></td></tr>
			<table>
			== Evolutionary Conservation ==
			[[Image:Consurf_key_small.gif\|200px\|right]]
			Check<jmol>
			<jmolCheckbox>
			<scriptWhenChecked>select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/ec/3ecb_consurf.spt"</scriptWhenChecked>
			<scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
			<text>to colour the structure by Evolutionary Conservation</text>
			</jmolCheckbox>
			</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary\|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/chain_selection.php?pdb_ID=2ata ConSurf].
			<div style="clear:both"></div>
			<div style="background-color:#fffaf0;">
			== Publication Abstract from PubMed ==
			In the immune system, B cells, dendritic cells, NK cells, and T lymphocytes all respond to signals received via ligand binding to receptors and coreceptors. Although the specificity of T cell recognition is determined by the interaction of T cell receptors with MHC/peptide complexes, the development of T cells in the thymus and their sensitivity to Ag are also dependent on coreceptor molecules CD8 (for MHC class I (MHCI)) and CD4 (for MHCII). The CD8alphabeta heterodimer is a potent coreceptor for T cell activation, but efforts to understand its function fully have been hampered by ignorance of the structural details of its interactions with MHCI. In this study we describe the structure of CD8alphabeta in complex with the murine MHCI molecule H-2D(d) at 2.6 A resolution. The focus of the CD8alphabeta interaction is the acidic loop (residues 222-228) of the alpha3 domain of H-2D(d). The beta subunit occupies a T cell membrane proximal position, defining the relative positions of the CD8alpha and CD8beta subunits. Unlike the CD8alphaalpha homodimer, CD8alphabeta does not contact the MHCI alpha(2)- or beta(2)-microglobulin domains. Movements of the CD8alpha CDR2 and CD8beta CDR1 and CDR2 loops as well as the flexibility of the H-2D(d) CD loop facilitate the monovalent interaction. The structure resolves inconclusive data on the topology of the CD8alphabeta/MHCI interaction, indicates that CD8beta is crucial in orienting the CD8alphabeta heterodimer, provides a framework for understanding the mechanistic role of CD8alphabeta in lymphoid cell signaling, and offers a tangible context for design of structurally altered coreceptors for tumor and viral immunotherapy.

	~~{{STRUCTURE_3ecb\| PDB=3ecb \| SCENE= }}~~		Structural basis of the CD8 alpha beta/MHC class I interaction: focused recognition orients CD8 beta to a T cell proximal position.,Wang R, Natarajan K, Margulies DH J Immunol. 2009 Aug 15;183(4):2554-64. Epub 2009 Jul 22. PMID:19625641<ref>PMID:19625641</ref>

	~~===Crystal structure~~ of ~~mouse H-2Dd in complex with peptide P18-I10 derived from human immunodeficiency virus envelope glycoprotein 120===~~		From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br>
			</div>
	~~{{ABSTRACT_PUBMED_19625641}}~~

	~~==About this Structure==~~
	~~[[3ecb]] is a 3 chain structure with sequence from [http://en~~.~~wikipedia~~.~~org/wiki/Mus_musculus Mus musculus]~~. ~~Full crystallographic information is available from [http://oca.weizmann.ac.il~~/~~oca-bin/ocashort?id=3ECB OCA].~~

	==See Also==		==See Also==
	*[[Beta-2 microglobulin\|Beta-2 microglobulin]]		*[[Beta-2 microglobulin\|Beta-2 microglobulin]]
	*[[Major histocompatibility complex\|Major histocompatibility complex]]		*[[Major histocompatibility complex\|Major histocompatibility complex]]
			== References ==
	==~~Reference~~==		<references/>
	<~~ref group="xtra">PMID:019625641<~~/~~ref~~><~~references group="xtra"~~/>		__TOC__
			</StructureSection>
	[[Category: Mus musculus]]		[[Category: Mus musculus]]
	[[Category: Margulies, D H.]]		[[Category: Margulies, D H.]]

OCA at 07:18, 20 October 2012

2012-10-20T07:18:20Z

← Older revision		Revision as of 07:18, 20 October 2012
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	==About this Structure==		==About this Structure==
	[[3ecb]] is a 3 chain structure ~~of [[Beta-2 microglobulin]] and [[Major histocompatibility complex]]~~ with sequence from [http://en.wikipedia.org/wiki/Mus_musculus Mus musculus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3ECB OCA].		[[3ecb]] is a 3 chain structure with sequence from [http://en.wikipedia.org/wiki/Mus_musculus Mus musculus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3ECB OCA].

	==See Also==		==See Also==

OCA: Protected "3ecb" [edit=sysop:move=sysop]

2012-07-25T15:54:06Z

Protected "3ecb" [edit=sysop:move=sysop]

← Older revision	Revision as of 15:54, 25 July 2012
(No difference)

OCA at 15:54, 25 July 2012

2012-07-25T15:54:04Z

← Older revision		Revision as of 15:54, 25 July 2012
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	~~{{Seed}}~~
	[[Image:3ecb.png\|left\|200px]]		[[Image:3ecb.png\|left\|200px]]

	~~<!--~~
	~~The line below this paragraph, containing "STRUCTURE_3ecb", creates the "Structure Box" on the page.~~
	~~You may change the PDB parameter (which sets the PDB file loaded into the applet)~~
	~~or the SCENE parameter (which sets the initial scene displayed when the page is loaded),~~
	~~or leave the SCENE parameter empty for the default display.~~
	~~-->~~
	{{STRUCTURE_3ecb\| PDB=3ecb \| SCENE= }}		{{STRUCTURE_3ecb\| PDB=3ecb \| SCENE= }}

	===Crystal structure of mouse H-2Dd in complex with peptide P18-I10 derived from human immunodeficiency virus envelope glycoprotein 120===		===Crystal structure of mouse H-2Dd in complex with peptide P18-I10 derived from human immunodeficiency virus envelope glycoprotein 120===


	~~<!--~~
	~~The line below this paragraph, {{ABSTRACT_PUBMED_19625641}}, adds the Publication Abstract to the page~~
	~~(as it appears on PubMed at http://www.pubmed.gov), where 19625641 is the PubMed ID number.~~
	~~-->~~
	{{ABSTRACT_PUBMED_19625641}}		{{ABSTRACT_PUBMED_19625641}}

	==About this Structure==		==About this Structure==
	~~3ECB~~ is a 3 ~~chains~~ structure of ~~sequences~~ from [http://en.wikipedia.org/wiki/Mus_musculus Mus musculus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3ECB OCA].		[[3ecb]] is a 3 chain structure of [[Beta-2 microglobulin]] and [[Major histocompatibility complex]] with sequence from [http://en.wikipedia.org/wiki/Mus_musculus Mus musculus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3ECB OCA].

			==See Also==
			*[[Beta-2 microglobulin\|Beta-2 microglobulin]]
			*[[Major histocompatibility complex\|Major histocompatibility complex]]

	==Reference==		==Reference==
	<ref group="xtra">PMID:~~19625641~~</ref><references group="xtra"/>		<ref group="xtra">PMID:019625641</ref><references group="xtra"/>
	[[Category: Mus musculus]]		[[Category: Mus musculus]]
	[[Category: Margulies, D H.]]		[[Category: Margulies, D H.]]
Line 33:		Line 25:
	[[Category: Class i major histompatibility complex]]		[[Category: Class i major histompatibility complex]]
	[[Category: Cleavage on pair of basic residue]]		[[Category: Cleavage on pair of basic residue]]
	~~[[Category: Coiled coil]]~~
	[[Category: Envelope protein]]		[[Category: Envelope protein]]
	[[Category: Fusion protein]]		[[Category: Fusion protein]]
Line 52:		Line 43:
	[[Category: Viral immunoevasion]]		[[Category: Viral immunoevasion]]
	[[Category: Virion]]		[[Category: Virion]]

	~~''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Sep 3 15:33:13 2009''~~