Background
This gene encodes a component of the complement system, a part of the innate immune
system that plays an important role in inflammation, host homeostasis, and host defense
against pathogens. The encoded preproprotein is proteolytically processed to generate
multiple protein products, including the C5 alpha chain, C5 beta chain, C5a anaphylatoxin
and C5b. The C5 protein is comprised of the C5 alpha and beta chains, which are linked by a
disulfide bridge. Cleavage of the alpha chain by a convertase enzyme results in the
formation of the C5a anaphylatoxin, which possesses potent spasmogenic and chemotactic
activity, and the C5b macromolecular cleavage product, a subunit of the membrane attack
complex (MAC). Mutations in this gene cause complement component 5 deficiency, a
disease characterized by recurrent bacterial infections. Alternative splicing results in
multiple transcript variants.
