View source for 9tdl


==Complex between complement C5 and cobra venom factor, re-refined==
<StructureSection load='9tdl' size='340' side='right'caption='[[9tdl]], [[Resolution|resolution]] 4.30&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[9tdl]] is a 10 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] and [https://en.wikipedia.org/wiki/Naja_kaouthia Naja kaouthia]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=9TDL OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=9TDL FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 4.3&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=NAG:N-ACETYL-D-GLUCOSAMINE'>NAG</scene></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=9tdl FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=9tdl OCA], [https://pdbe.org/9tdl PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=9tdl RCSB], [https://www.ebi.ac.uk/pdbsum/9tdl PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=9tdl ProSAT]</span></td></tr>
</table>
== Disease ==
[https://www.uniprot.org/uniprot/CO5_HUMAN CO5_HUMAN] Defects in C5 are the cause of complement component 5 deficiency (C5D) [MIM:[https://omim.org/entry/609536 609536]. A rare defect of the complement classical pathway associated with susceptibility to severe recurrent infections, predominantly by Neisseria gonorrhoeae or Neisseria meningitidis.  Note=An association study of C5 haplotypes and genotypes in individuals with chronic hepatitis C virus infection shows that individuals homozygous for the C5_1 haplotype have a significantly higher stage of liver fibrosis than individuals carrying at least 1 other allele (PubMed:15995705).
== Function ==
[https://www.uniprot.org/uniprot/CO5_HUMAN CO5_HUMAN] Activation of C5 by a C5 convertase initiates the spontaneous assembly of the late complement components, C5-C9, into the membrane attack complex. C5b has a transient binding site for C6. The C5b-C6 complex is the foundation upon which the lytic complex is assembled.  Derived from proteolytic degradation of complement C5, C5 anaphylatoxin is a mediator of local inflammatory process. It induces the contraction of smooth muscle, increases vascular permeability and causes histamine release from mast cells and basophilic leukocytes. C5a also stimulates the locomotion of polymorphonuclear leukocytes (chemokinesis) and direct their migration toward sites of inflammation (chemotaxis).
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== Publication Abstract from PubMed ==
Complement acts as a danger-sensing system in the innate immune system, and its activation initiates a strong inflammatory response and cleavage of the proteins C3 and C5 by proteolytic enzymes, the convertases. These contain a non-catalytic substrate contacting subunit (C3b or C4b) in complex with a protease subunit (Bb or C2a). We determined the crystal structures of the C3b homologue cobra venom factor (CVF) in complex with C5, and in complex with C5 and the inhibitor SSL7 at 4.3 A resolution. The structures reveal a parallel two-point attachment between C5 and CVF, where the presence of SSL7 only slightly affects the C5-CVF interface, explaining the IgA dependence for SSL7-mediated inhibition of C5 cleavage. CVF functions as a relatively rigid binding scaffold inducing a conformational change in C5, which positions its cleavage site in proximity to the serine protease Bb. A general model for substrate recognition by the convertases is presented based on the C5-CVF and C3b-Bb-SCIN structures. Prior knowledge concerning interactions between the endogenous convertases and their substrates is rationalized by this model.

Substrate recognition by complement convertases revealed in the C5-cobra venom factor complex.,Laursen NS, Andersen KR, Braren I, Spillner E, Sottrup-Jensen L, Andersen GR EMBO J. 2011 Jan 7. PMID:21217642<ref>PMID:21217642</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 9tdl" style="background-color:#fffaf0;"></div>
== References ==
<references/>
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</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Naja kaouthia]]
[[Category: Andersen GR]]