Complement C3
ContentsFunctionComplement 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.[1] C3b α and β chains with protein CRIG and Ca+2 ion. Ca+2 ion coordination site (PDB code 2icf).[2] DiseaseA mutation in CC3 cause the progressive kidney disease: dense deposit disease. Other mutations are associated with recurrent bacterial infections. RelevanceLow levels of CC3 in the blood are associated with some kidney diseases.
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3D structures of complement C3
Updated on 18-July-2018
- Complement C3
- Complement C3a (anaphylatoxin)
- Complement C3b
- 2i07, 5fo7 – hCC3 β+α’ chains
- 5fob – hCC3 β+α’ chains + inhibitor
- 5fo9 – hCC3 β+α’ chains + protein
- 5foa, 5f08, 2icf, 2wii – hCC3 α+β chains + protein
- 3g6j, 6ehg – hCC3 α+β chains + antibody
- 5o35 – hCC3 α chain + complement factor H
- 5o32 – hCC3 α chain + complement factor I
- 2xwb – hCC3 α+β chains + complement factor B + complement factor D
- 2xwj – hCC3 α+β chains (mutant) + complement factor B
- 5nbq – hCC3 α chain + complement factor B
- 5fo8 – hCC3 α chain + membrane cofactor protein
- 5m6w – hCC3 α+β chains + complement factor H + complement inhibitor
- 3l5n, 3ohx – hCC3 α+β chains + protein inhibitor
- 2win – hCC3 α+β chains + complement factor B BB fragment + protein inhibitor
- 2i07, 5fo7 – hCC3 β+α’ chains
- Complement C3c
- Complement C3d
- 5fcr – CC3 - mouse
- 1c3d – hCC3 (mutant)
- 1w2s, 3oed – hCC3 1-2 sushi domains + complement receptor type 2 precursor
- 2gox, 3d5r, 3d5s – hCC3 α chain fragment + fibrinogen-binding protein
- 2noj – hCC3 α chain fragment (mutant) + EFB homologous protein
- 2wy7, 2wy8 – hCC3 α chain fragment (mutant) + IGG-binding protein
- 3oxu – hCC3 α chain fragment (mutant) + HF protein
- 4m76 – hCC3 α chain fragment (mutant) + integrin α-M
- 2xqw – hCC3 + complement factor H 19-20 sushi domains
- 3rj3 – hCC3 α chain fragment + complement factor H-related protein
- 5mt0, 5mt4, 5tca, 5tcc, 5fbe, 5fbi, 5fck – hCC3 + inhibitor
- 1qqf – rCC3 G fragment - rat
- 1qsj – rCC3 G fragment (mutant)
- 5fcr – CC3 - mouse