A glycoprotein that is central in both the classical and the alternative pathway of COMPLEMENT ACTIVATION. C3 can be cleaved into COMPLEMENT C3A and COMPLEMENT C3B, spontaneously at low level or by C3 CONVERTASE at high level. The smaller fragment C3a is an ANAPHYLATOXIN and mediator of local inflammatory process. The larger fragment C3b binds with C3 convertase to form C5 convertase.

Synonyms: Complement, C3, Complement C3, Pro Complement 3, C3 Complement, Pro-Complement 3, Complement 3, Precursor-Complement 3, Pro-C3, Precursor, Complement C3, Complement C3 Precursor, 0, Precursor, C3, Complement Component 3, Precursor Complement 3, C3 Precursor, C3 Precursor, Complement, Component 3, Complement, C3, Complement, Pro C3