Complement Factor D (Adipsin)

Complement Factor D, also known as adipsin, is a serine protease that catalyzes the initial proteolytic step in the alternative pathway of complement. It is an exceptionally specific protease and the only known protein substrate is factor B in complex with C3.3 Factor D protease activity is regulated by reversible conformational changes, which differs from the majority of serine proteases whose regulation involves either activation by processing of the zymogens or inactivation by binding of the inhibitors.