Complement C8A/B/G Products

C8 is synthesised in the liver, monocytes and fibroblasts and is a plasma protein consisting of three non identical polypeptide chains. The alpha-chain (64kDa) and gamma chain (22kDa) are disulphide linked, these associate non-covalently with the beta-chain (64kDa), to form the native C8 molecule with a molecular weight of 151kDa. Normal plasma concentration is 80mg/L.C8 is one of the terminal proteins of the complement pathways. C8 binds to the membrane bound C5b-7, C5b-8 combines with C9 to form the membrane attack complex (MAC). The MAC forms a hydrophilic, protein walled, transmembrane channel, formation of which leads to cell lysis and destruction.