Native human C7 is a naturally glycosylated protein composed of a single polypeptide chain of 92,400 Da. C7 is essential for formation of the membrane attack complex (MAC) and is activated non-proteolytically by binding to recently-formed C5b,C6 complexes at the cell membrane. Each pathway of complement activation generates proteolytic enzyme complexes which are bound to the target surface. Description: Human serum/plasma. Synonyms: C& protein.