Complement Component 6

Complement component 6 (C6) is one of the terminal complement components that assemble the membrane attack complex (MAC). This single-chain plasma glycoprotein is built from repeated thrombospondin, LDL-receptor, and EGF-like modules arranged into canonical complement protein domains. Once C5b is generated on an activating surface, C6 binds C5b directly to form the stable C5b-6 intermediate, to which C7 subsequently attaches and commits the complex to membrane insertion. Inherited C6 deficiency, described in several populations worldwide, predisposes carriers to recurrent Neisseria meningitidis infections. Recombinant C6 and related terminal-pathway proteins are used to dissect MAC assembly in complement research.