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.[1]
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.(PDB code 2icf)
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.
