ID 3.4.21.43 DE classical-complement-pathway C3/C5 convertase. AN C3 convertase. AN C5 convertase. AN complement C2. CA Selective cleavage of Arg-|-Ser bond in complement component C3 alpha- CA chain to form C3a and C3b, and Arg-|-Xaa bond in complement component C5 CA alpha-chain to form C5a and C5b. CC -!- A complex of complement fragments C4b, C2a and C2b. CC -!- Belongs to peptidase family S1. CC -!- Formerly EC 3.4.21.44. DR Q3SYW2, CO2_BOVIN ; Q863A0, CO2_GORGO ; P06681, CO2_HUMAN ; DR P21180, CO2_MOUSE ; Q8SQ74, CO2_PANTR ; Q8SQ75, CO2_PONPY ; //