Ricin: Difference between revisions

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{{BAMBED
|DATE=May 14, 2013
|OLDID=1797961
|BAMBEDDOI=10.1002/bmb.20716
}}
'''Ricin''' is a potent cytotoxin that is synthesized in the endosperm cells of maturing seeds of the castor oil plant (''Ricinus communis'')<ref name="lord">PMID: 8119491</ref>. Ricin belongs to a small multi-gene family<ref name="montfort">PMID: 3558397</ref> that is composed of eight members. Ricin is classified as a type II heterodimeric Ribosome Inactivating Protein<ref name="lord" /> or RIPs.  For toxins in Proteopedia see [[Toxins]].
'''Ricin''' is a potent cytotoxin that is synthesized in the endosperm cells of maturing seeds of the castor oil plant (''Ricinus communis'')<ref name="lord">PMID: 8119491</ref>. Ricin belongs to a small multi-gene family<ref name="montfort">PMID: 3558397</ref> that is composed of eight members. Ricin is classified as a type II heterodimeric Ribosome Inactivating Protein<ref name="lord" /> or RIPs.  For toxins in Proteopedia see [[Toxins]].


<StructureSection load='3rtj'  size='400' side='right' caption='Glycosylated ricin chain A (grey) and chain B (green) bound to dinucleotide APG (stick model) (PDB entry [[3rtj]])'>
See also [[Ricin: A toxic protein]]; [[Ricin: Structure and function]].
 
<StructureSection load='3rtj'  size='350' side='right' caption='Glycosylated ricin chain A (grey) and chain B (green) bound to dinucleotide APG (stick model) (PDB entry [[3rtj]])'>
==Structure==
==Structure==
Ricin is a heterodimer that consists of a 32 kilodalton A chain glycoprotein (light blue) linked by a <scene name='38/382952/Disulfide_bond_between_subunit/3'>disulfide bond</scene> to a 32 kilodalton <scene name='Sandbox_BCMB402_Ricin/B_subunit/1'>B chain</scene> glycoprotein<ref name="montfort" /> (green).  
Ricin is a heterodimer that consists of a 32 kilodalton A chain glycoprotein (light blue) linked by a <scene name='38/382952/Disulfide_bond_between_subunit/3'>disulfide bond</scene> to a 32 kilodalton <scene name='Sandbox_BCMB402_Ricin/B_subunit/1'>B chain</scene> glycoprotein<ref name="montfort" /> (green).  
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The <scene name='Sandbox_BCMB402_Ricin/A_subunit_secondary_structure/2'> A chain</scene> is an alpha/beta protein which contains eight alpha helices (pink) and eight beta sheets (yellow). It has three domains<ref name="Weston">PMID: 7990130</ref>.  <scene name='Sandbox_BCMB402_Ricin/Domain_1_of_a_subunit/2'>Domain 1 </scene> consists of a beta sheet containing both parallel and anti-parallel strands.  The <scene name='Sandbox_BCMB402_Ricin/Domain2_of_a_subunit/1'> second alpha helical domain </scene> makes up the core of the protein, and includes the active site.  The<scene name='Sandbox_BCMB402_Ricin/Domain3_of_a_subunit/1'> third domain</scene> interacts with the B chain, and contains a helix and two beta strands.
The <scene name='Sandbox_BCMB402_Ricin/A_subunit_secondary_structure/2'> A chain</scene> is an alpha/beta protein which contains eight alpha helices (pink) and eight beta sheets (yellow). It has three domains<ref name="Weston">PMID: 7990130</ref>.  <scene name='Sandbox_BCMB402_Ricin/Domain_1_of_a_subunit/2'>Domain 1 </scene> consists of a beta sheet containing both parallel and anti-parallel strands.  The <scene name='Sandbox_BCMB402_Ricin/Domain2_of_a_subunit/1'> second alpha helical domain </scene> makes up the core of the protein, and includes the active site.  The<scene name='Sandbox_BCMB402_Ricin/Domain3_of_a_subunit/1'> third domain</scene> interacts with the B chain, and contains a helix and two beta strands.


The A chain contains the active site that is responsible for inactivating the [[Ribosome]] via depurination.  RIPs have very diverse structures, containing only eight invariant residues<ref name = "lord"/>.  These <scene name='Sandbox_BCMB402_Ricin/Conserved_residues/2'>conserved residues</scene> are clustered in the active site.
The '''A chain''' contains the active site that is responsible for inactivating the [[Ribosome]] via depurination.  RIPs have very diverse structures, containing only eight invariant residues<ref name = "lord"/>.  These <scene name='Sandbox_BCMB402_Ricin/Conserved_residues/2'>conserved residues</scene> are clustered in the active site.


The B chain is a lectin<ref name="lord" /> that <scene name='Sandbox_BCMB402_Ricin/Carbohydrate_binding/1'>binds</scene> to galactose-containing surface receptors.  Originally it was thought that the mode of action of Ricin poisoning was due to hemagglutination due to a closely related, co-isolating lectin, RCA.  
The '''B chain''' is a lectin<ref name="lord" /> that <scene name='Sandbox_BCMB402_Ricin/Carbohydrate_binding/1'>binds</scene> to galactose-containing surface receptors.  Originally it was thought that the mode of action of Ricin poisoning was due to hemagglutination due to a closely related, co-isolating lectin, RCA.  


==Mechanism of action==
==Mechanism of action==
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</StructureSection>
</StructureSection>


==3D structures of ricin (Updated on {{REVISIONDAY2}}-{{MONTHNAME|{{REVISIONMONTH}}}}-{{REVISIONYEAR}}) ==
==3D structures of ricin==
{{#tree:id=OrganizedByTopic|openlevels=0|
[[Ricin 3D structures]]
* Ricin A chain (RTA)
** [[1j1m]], [[1ift]], [[2aai]], [[1rtc]] – RTA<br />
** [[3lc9]], [[3mk9]], [[2vc4]], [[1uq4]], [[1uq5]], [[1obs]], [[3bjg]], [[3srp]], [[4imv]] – RTA (mutant)
 
* Ricin A chain binary complexes''
 
** [[3px8]] – RTA preproricin + 7-carboxy-pterin<br />
** [[1br5]], [[1br6]], [[4esi]], [[4huo]], [[4hup]], [[4hv3]], [[4hv7]], [[4mx1]], [[4mx5]] - RTA + pterin derivative<br />
** [[3px9]] - RTA preproricin + furanylmethyl-carbamoyl-pterin<br />
** [[3lc9]], [[3mk9]], [[2vc4]], [[1uq4]], [[1uq5]], [[1obs]] – RTA (mutant) <br />
** [[3hio]] – RTA + tetranucleotide<br />
** [[3ej5]], [[1il5]] – RTA pyrimidine derivative<br />
** [[2p8n]], [[1ifs]] – RTA + adenine<br />
** [[2pjo]], [[2r2x]] – RTA + urea derivative<br />
** [[2r3d]] – RTA + acetamide<br />
** [[2vc3]] - RTA (mutant) + acetate<br />
** [[1il3]], [[1il4]], [[1il9]] – RTA + guanine derivative<br />
** [[1ifu]], [[1fmp]] – RTA + formycin<br />
** [[1obt]] - RTA (mutant) + AMP<br />
** [[1apg]] – RTA + RNA
** [[3px8]] – RTA + formycin monophosphate<br />
** [[4kuc]] – RTA + antibody<br />
 
* Ricin B chain (RTB)
 
** [[3nbc]], [[3nbd]] – CnRTB + lactose – ''Clitocybe nebularis''<br />
** [[3nbe]] – CnRTB + lactose derivative<br />
** [[3phz]] – RTB + glycoside – ''Polyporus squamosus''<br />
** [[3vsf]] – CtRTB lectin domain – ''Clostridium thermocellum''<br />
** [[3vsz]] – CtRTB lectin domain + galactan<br />
** [[3vto]] – CtRTB lectin domain + lactose<br />
** [[3vt1]], [[3vt2]] – CtRTB lectin domain + galactose derivative<br />
 
* Ricin A+B chains


** [[2aai]] - RTA + RTB<br />
** [[3px8]], [[3rti]] – RTA + RTB + formycin monophosphate<br />
** [[3rtj]] - RTA + RTB + dinucleotide
}}
==See Also==
==See Also==
* [[Ribosome]]
* [[Ribosome]]
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[[Category: Topic Page]]
[[Category: Topic Page]]
[[Category:Featured in BAMBED]]
Retrieved from "https://proteopedia.org/Ricin"