Complement C9 from human serum is an essential part of the terminal complement system. It has been a topic in cancer research, where extracellular phosphorylation by ecto-PK of K562 cells on serine residues may serve as a protective mechanism against complement in tumor cells. Additionally, it can be used as a biomarker (in fucosylated form) for squamous cell lung cancer, as patients tend to show elevated levels of C9 protein.
Complement component C9 is the final component of the membrane attack complex (MAC) responsible for cell lysis by complement. CD59 binds to both C8 and C9 and prevents assembly of an active MAC, protecting cells against lytic activity.
View more information on the complement pathway at www.sigma-aldrich.com/enzymeexplorer
Supplied as a solution in phosphate buffered saline, pH 7.2.
Functionally pure by a sensitive hemolytic assay using deficient sera.