Recombinant Human Complement component C8 gamma chain (C8G)

Function

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: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). C8G, together with C8A and C8B, inserts into the target membrane, but does not form pores by itself (PubMed:30552328). During MAC assembly, associates with C5b, C6 and C7 to form the C5b8 intermediate complex that inserts into the target membrane and traverses the bilayer increasing membrane rigidity (PubMed:30552328, PubMed:6833260)

Subcellular Location

Secreted; Target cell membrane

Subunit

Heterotrimer of 3 chains: alpha (C8A), beta (C8B) and gamma (C8G); the alpha and gamma chains are disulfide bonded (PubMed:17692377, PubMed:21454577). Component of the membrane attack complex (MAC), composed of complement C5b, C6, C7, C8A, C8B, C8G and multiple copies of the pore-forming subunit C9 (PubMed:26841837, PubMed:27052168, PubMed:30552328, PubMed:31061395)

• Ng S.C. et al. The eighth component of human complement: evidence that it is an oligomeric serum protein assembled from products of three different genes. — Biochemistry (1987)
• Haefliger J.-A. et al. Structural homology of human complement component C8 gamma and plasma protein HC: identity of the cysteine bond pattern. — Biochem. Biophys. Res. Commun. (1987)
• Kaufman K.M. et al. Genomic structure of the human complement protein C8 gamma: homology to the lipocalin gene family. — Biochemistry (1994)
• Humphray S.J. et al. DNA sequence and analysis of human chromosome 9. — Nature (2004)
• Mural R.J. et al. PubMed: CI-5GBDQ6B103N1E (JUL-)
• The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC). — Genome Res. (2004)
• Steckel E.W. et al. Evidence of direct insertion of terminal complement proteins into cell membrane bilayers during cytolysis. Labeling by a photosensitive membrane probe reveals a major role for the eighth and ninth components. — J. Biol. Chem. (1983)
• Hunt L.T. et al. The homology of complement factor C8 gamma chain and alpha-1-microglobulin. — Biochem. Biophys. Res. Commun. (1987)