Component of the membrane attack complex (MAC), a multiprotein complex activated by the complement cascade, which inserts into a target cell membrane and forms a pore, leading to target cell membrane rupture and cell lysis (PubMed:22832194, PubMed:26841837, PubMed:27052168, PubMed:30552328, PubMed:3335508). The MAC is initiated by proteolytic cleavage of C5 into complement C5b in response to the classical, alternative, lectin and GZMK complement pathways (PubMed:22832194, PubMed:30552328, PubMed:3335508, PubMed:39914456, PubMed:39814882). The complement pathways consist in a cascade of proteins that leads to phagocytosis and breakdown of pathogens and signaling that strengthens the adaptive immune system (PubMed:22832194, PubMed:30552328, PubMed:3335508). C7 serves as a membrane anchor (PubMed:30552328). During MAC assembly, associates with C5b and C6 to form the C5b-7 complex, a key lipophilic precursor of the MAC complex, which associates with the outer leaflet and reduces the energy for membrane bending (PubMed:30552328, PubMed:32569291). {ECO:0000269|PubMed:22832194, ECO:0000269|PubMed:26841837, ECO:0000269|PubMed:27052168, ECO:0000269|PubMed:30552328, ECO:0000269|PubMed:32569291, ECO:0000269|PubMed:3335508, ECO:0000269|PubMed:39814882, ECO:0000269|PubMed:39914456}. This is the function of C7 (complement C7, Ensembl gene identifier ENSG00000112936).