Constituent of the membrane attack complex (MAC) that plays a key role in the innate and adaptive immune response by forming pores in the plasma membrane of target cells ( ). C9 is the pore-forming subunit of the MAC ( ).
Subcellular locations: Secreted, Target cell membrane
Secreted as soluble monomer. Oligomerizes at target membranes, forming a pre-pore. A conformation change then leads to the formation of a 100 Angstrom diameter pore.
Plasma (at protein level).