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:22267737, PubMed:22832194, PubMed:26841837, PubMed:27052168, PubMed:30552328). The MAC is initiated by proteolytic cleavage of C5 into complement C5b in response to the classical, alternative, lectin and GZMK complement pathways (PubMed:30552328, 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:30552328). Together with component C5b, involved in MAC complex assembly: complement C5b and C6 associate with the outer leaflet of target cell membrane, reducing the energy for membrane bending (PubMed:30552328, PubMed:32569291). {ECO:0000269|PubMed:22267737, ECO:0000269|PubMed:22832194, ECO:0000269|PubMed:26841837, ECO:0000269|PubMed:27052168, ECO:0000269|PubMed:30552328, ECO:0000269|PubMed:32569291, ECO:0000269|PubMed:39814882, ECO:0000269|PubMed:39914456}. This is the function of C6 (complement C6, ENSG00000039537).