Ricin: Difference between revisions
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<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]])'> | <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]])'> | ||
==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 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== | ||
The mechanism deployed by Ricin to gain entry to a host cell involves the poison's heterogenic properties. First, the B subunit binds to two carbohydrates on the cell surface, either glycolipids or glycoproteins, which both terminate with galactose. The interaction is facilitated by hydrogen bonds to <scene name='Sandbox_BCMB402_Ricin/B_chain_bind_lactose_1/2'>lysine 40 and asparagine 46</scene> in one domain<ref name = "Rutenber">PMID: 3561502</ref> and <scene name='Sandbox_BCMB402_Ricin/B_chain_bind_lactose_2/1'>asparagine 255</scene> in the other domain. Once bound, the ricin-glycoprotein complex is taken into the cells via endocytosis. This association between the A and B chain is essential for toxicity <ref name="montfort" /> without it the Ricin would not be able to gain access to the cell, rendering it useless<ref name = "rapak">PMID: 9108055</ref>. The endocytotic pathway results in the cleavage of the disulfide bond linking the A and B chains. After cleavage, the A chain is released into the cytosol. | The mechanism deployed by Ricin to gain entry to a host cell involves the poison's heterogenic properties. First, the B subunit binds to two carbohydrates on the cell surface, either glycolipids or glycoproteins, which both terminate with galactose. The interaction is facilitated by hydrogen bonds to <scene name='Sandbox_BCMB402_Ricin/B_chain_bind_lactose_1/2'>lysine 40 and asparagine 46</scene> in one domain<ref name = "Rutenber">PMID: 3561502</ref> and <scene name='Sandbox_BCMB402_Ricin/B_chain_bind_lactose_2/1'>asparagine 255</scene> in the other domain. Once bound, the ricin-glycoprotein complex is taken into the cells via endocytosis. This association between the A and B chain is essential for toxicity <ref name="montfort" /> without it the Ricin would not be able to gain access to the cell, rendering it useless<ref name = "rapak">PMID: 9108055</ref>. The endocytotic pathway results in the cleavage of the disulfide bond linking the A and B chains. After cleavage, the A chain is released into the cytosol. | ||
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Updated on {{REVISIONDAY2}}-{{MONTHNAME|{{REVISIONMONTH}}}}-{{REVISIONYEAR}} | Updated on {{REVISIONDAY2}}-{{MONTHNAME|{{REVISIONMONTH}}}}-{{REVISIONYEAR}} | ||
===Ricin A chain (RTA)=== | ===Ricin A chain (RTA)=== | ||
[[1j1m]], [[1ift]], [[2aai]], [[1rtc]] – RTA<br /> | [[1j1m]], [[1ift]], [[2aai]], [[1rtc]] – RTA<br /> | ||
[[3lc9]], [[3mk9]], [[2vc4]], [[1uq4]], [[1uq5]], [[1obs]], [[3bjg]], [[3srp]], [[4imv]] – RTA (mutant) | [[3lc9]], [[3mk9]], [[2vc4]], [[1uq4]], [[1uq5]], [[1obs]], [[3bjg]], [[3srp]], [[4imv]] – RTA (mutant) | ||
''Ricin A chain binary complexes'' | |||
[[3px8]] – RTA preproricin + 7-carboxy-pterin<br /> | [[3px8]] – RTA preproricin + 7-carboxy-pterin<br /> | ||
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[[3px8]] – RTA + formycin monophosphate<br /> | [[3px8]] – RTA + formycin monophosphate<br /> | ||
[[4kuc]] – RTA + antibody<br /> | [[4kuc]] – RTA + antibody<br /> | ||
===Ricin B chain (RTB)=== | ===Ricin B chain (RTB)=== | ||
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[[3vt1]], [[3vt2]] – CtRTB lectin domain + galactose derivative<br /> | [[3vt1]], [[3vt2]] – CtRTB lectin domain + galactose derivative<br /> | ||
===Ricin A+B chains=== | ===Ricin A+B chains=== | ||
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[[3rtj]] - RTA + RTB + dinucleotide | [[3rtj]] - RTA + RTB + dinucleotide | ||
==See Also== | ==See Also== | ||
* [[Ribosome]] | * [[Ribosome]] | ||
* [[Large Ribosomal Subunit of Haloarcula|Large Ribosomal Subunit]] | * [[Large Ribosomal Subunit of Haloarcula|Large Ribosomal Subunit]] | ||
* [[Translation]] | * [[Translation]] | ||
==References== | ==References== | ||
{{Reflist}} | {{Reflist}} | ||
[[Category: Topic Page]] | [[Category: Topic Page]] | ||