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].
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(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
