C6
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: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).
Involvement in disease
Complement component 6 deficiency
C6D
A rare defect of the complement classical pathway associated with susceptibility to severe recurrent infections, predominantly by Neisseria gonorrhoeae or Neisseria meningitidis.
None
Disease susceptibility is associated with variants affecting the gene represented in this entry.
Post-translational modifications
All cysteine residues are assumed to be cross-linked to one another. Individual modules containing an even number of conserved cysteine residues are supposed to have disulfide linkages only within the same module.
Sequence Similarities
Belongs to the complement C6/C7/C8/C9 family.
Cellular localization
- Secreted
- Target cell membrane
- Multi-pass membrane protein
- Secreted as soluble protein (PubMed:2808363). Inserts into the cell membrane of target cells (PubMed:30552328, PubMed:31061395).
Alternative names
Complement component C6, C6