Complement C3: Difference between revisions

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== Function ==
== Function ==


'''Complement C3''' (CC3) activates the complement system which is part of the immune response.  CC3 is proteolytically cleaved by C3 convertase to C3a (residues 672-748) and C3b (residues 23-667, 749-1663).  C3a is a mediator of local inflammatory processes.  C3b binds covalently to cell surface carbohydrates or immune aggregates.  Breakdown of C3b generates the fragment C3d (residues 996-1287) which binds to antigens enhancing their uptake by B cells.  C3c is another C3b cleavage product residues: 23-664, 749-954, 1321-1663.<ref>PMID:11414361</ref>
'''Complement C3''' (CC3) activates the complement system which is part of the immune response.  '''CC3''' is proteolytically cleaved by C3 convertase to '''C3a''' (residues 672-748) and '''C3b''' (residues 23-667, 749-1663).   
*'''C3a''' is a mediator of local inflammatory processes.   
*'''C3b''' binds covalently to cell surface carbohydrates or immune aggregates.   
*'''C3c''' is another C3b cleavage product residues: 23-664, 749-954, 1321-1663.<ref>PMID:11414361</ref>
*'''C3d''' is a fragment generated by C3b(residues 996-1287) which binds to antigens enhancing their uptake by B cells<ref>PMID:17337780</ref>.


<scene name='59/594590/Cv/2'>C3b α and β chains with protein CRIG and Ca+2 ion</scene>.
<scene name='59/594590/Cv/2'>C3b α and β chains with protein CRIG and Ca+2 ion</scene>.


<scene name='59/594590/Cv/3'>Ca+2 ion coordination site</scene>.(PDB code [[2icf]])
<scene name='59/594590/Cv/4'>Ca+2 ion coordination site</scene> (PDB code [[2icf]]).<ref>PMID:17051150</ref>


== Disease ==
== Disease ==
Line 16: Line 20:


Low levels of CC3 in the blood are associated with some kidney diseases.
Low levels of CC3 in the blood are associated with some kidney diseases.
</StructureSection>


==3D structures of complement C3==
==3D structures of complement C3==
[[Complement C3 3D structures]]


Updated on {{REVISIONDAY2}}-{{MONTHNAME|{{REVISIONMONTH}}}}-{{REVISIONYEAR}}
</StructureSection>
{{#tree:id=OrganizedByTopic|openlevels=0|
 
*Complement C3
 
**[[2a73]] – hCC3 – human <br />
**[[1ghq]] – hCC3 residues 996-1300 + Epstein-Barr virus receptor <br />
**[[2b39]] – bCC3 – bovine <br />
 
*Complement C3a (anaphylatoxin)
 
**[[4hw5]], [[4hwj]], [[4i6o]] – hCC3  <br />
 
*Complement C3b
 
**[[2hr0]], [[2i07]] – hCC3  β+α’ chains<br />
**[[2icf]] – hCC3 α+β chains + protein CRIG<br />
**[[3g6j]] – hCC3 α+β chains + antibody<br />
**[[2xwb]] – hCC3 α+β chains + complement factor B + complement factor D<br />
**[[2xwj]] – hCC3 α+β chains (mutant) + complement factor B<br />
**[[2wii]] – hCC3 α+β chains + complement factor H 1-4 sushi domains<br />
**[[3l5n]], [[3ohx]] – hCC3 α+β chains + staphylococcal complement inhibitor<br />
**[[2win]] – hCC3 α+β chains + complement factor B BB fragment + staphylococcal complement inhibitor<br />
 
*Complement C3c
 
**[[2a74]] – hCC3  <br />
**[[2qki]] – hCC3 + compstatin <br />
**[[3l3o]], [[3nms]] – hCC3 + staphylococcal complement inhibitor<br />
**[[2ice]] – hCC3 α+β chains + protein CRIG<br />
**[[3t4a]] – hCC3 α+β chains + fibrinogen-binding protein <br />
 
*Complement C3d
 
**[[1c3d]] – hCC3 (mutant) <br />
**[[1w2s]], [[3oed]] – hCC3 1-2 sushi domains + complement receptor type 2 precursor<br />
**[[2gox]], [[3d5r]], [[3d5s]] – hCC3 α chain fragment + fibrinogen-binding protein <br />
**[[2noj]] – hCC3 α chain fragment (mutant) + EFB homologous protein <br />
**[[2wy7]], [[2wy8]] – hCC3 α chain fragment (mutant) + IGG-binding protein <br />
**[[3oxu]] – hCC3 α chain fragment (mutant) + HF protein <br />
**[[4m76]] – hCC3 α chain fragment (mutant) + integrin α-M <br />
**[[2xqw]] – hCC3  + complement factor H 19-20 sushi domains<br />
**[[3rj3]] – hCC3 α chain fragment + complement factor H-related protein<br />
**[[1qqf]] – rCC3 G fragment - rat <br />
**[[1qsj]] – rCC3 G fragment (mutant) <br />
}}
 
 
 
 


== References ==
== References ==

Latest revision as of 11:57, 5 June 2024

Function

Complement C3 (CC3) activates the complement system which is part of the immune response. CC3 is proteolytically cleaved by C3 convertase to C3a (residues 672-748) and C3b (residues 23-667, 749-1663).

  • C3a is a mediator of local inflammatory processes.
  • C3b binds covalently to cell surface carbohydrates or immune aggregates.
  • C3c is another C3b cleavage product residues: 23-664, 749-954, 1321-1663.[1]
  • C3d is a fragment generated by C3b(residues 996-1287) which binds to antigens enhancing their uptake by B cells[2].

.

(PDB code 2icf).[3]

Disease

A mutation in CC3 cause the progressive kidney disease: dense deposit disease. Other mutations are associated with recurrent bacterial infections.

Relevance

Low levels of CC3 in the blood are associated with some kidney diseases.

3D structures of complement C3

Complement C3 3D structures


Structure of human glycosylated complement C3b α (magenta) and β (salmon) chains complex with protein CRIG (cyan) and Ca+2 ion (green) (PDB code 2icf).

Drag the structure with the mouse to rotate

ReferencesReferences

  1. ↑ Sahu A, Lambris JD. Structure and biology of complement protein C3, a connecting link between innate and acquired immunity. Immunol Rev. 2001 Apr;180:35-48. PMID:11414361
  2. ↑ Toapanta FR, Ross TM. Complement-mediated activation of the adaptive immune responses: role of C3d in linking the innate and adaptive immunity. Immunol Res. 2006;36(1-3):197-210. PMID:17337780 doi:10.1385/IR:36:1:197
  3. ↑ Wiesmann C, Katschke KJ, Yin J, Helmy KY, Steffek M, Fairbrother WJ, McCallum SA, Embuscado L, DeForge L, Hass PE, van Lookeren Campagne M. Structure of C3b in complex with CRIg gives insights into regulation of complement activation. Nature. 2006 Nov 9;444(7116):217-20. Epub 2006 Oct 15. PMID:17051150 doi:10.1038/nature05263

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Michal Harel, Alexander Berchansky
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