This protein is composed of alpha and beta polypeptide chains that are linked by a disulfide bridge.

[5] Mutations in this gene cause complement component 5 deficiency, a disease where patients show a propensity for severe recurrent infections.

Defects in this gene have also been linked to a susceptibility to liver fibrosis and to rheumatoid arthritis.

[5] The drug eculizumab (trade name Soliris) prevents cleavage of C5 into C5a and C5b.

[7] This article incorporates text from the United States National Library of Medicine, which is in the public domain.