C7 Gene: Complement Component 7 – Function, Mutations, and Disease Associations

The C7 gene encodes complement component 7, a serum glycoprotein that is a critical structural component of the membrane attack complex (MAC). C7 is synthesized primarily in the liver and circulates in plasma. Upon complement activation, C7 binds to the C5b-6 complex, forming C5b-7, which inserts into the target cell membrane. This complex then recruits C8 and multiple C9 molecules to form a lytic pore, leading to osmotic lysis of pathogens. C7 deficiency is associated with increased susceptibility to recurrent Neisseria meningitidis and Neisseria gonorrhoeae infections.

Tissue Expression

Cell Line Expression

Hotspot Mutations

Mutation functional classification

• Complement cascade (KEGG: hsa04610)

• Staphylococcus aureus infection (KEGG: hsa05150)

• Tuberculosis (KEGG: hsa05152)

Complement component 7 (C7) is a 95 kDa single-chain glycoprotein composed of multiple domains including a CUB domain, a thrombospondin type-1 domain, and a MACPF domain. It is synthesized as a preproprotein and cleaved to yield the mature protein. C7 circulates in plasma at ~55 µg/mL. During complement activation, C7 binds to the C5b-6 complex via its CUB domain, inducing a conformational change that exposes a hydrophobic region allowing membrane insertion. This step is essential for subsequent C8 and C9 recruitment and formation of the lytic pore. C7 deficiency (OMIM #217070) is an autosomal recessive disorder characterized by recurrent Neisseria infections, but affected individuals may also have autoimmune manifestations.