Complement C4, Human

≥60% of the C4 activity present in freshly drawn normal human serum on a mg to mg basis

Toxicity: Standard Handling (A)

Native, human C4 complement component. Glycoprotein composed of three non-identical subunits of M.W. 93,000 (α), 75,000 (β), and 32,000 (γ) linked by disulfide bonds. Present in normal human serum at 400 µg/ml. On activation of complement via the classical pathway, the C1s subcomponent of the C1 complex is converted to an active serine protease that cleaves the C4 α-chain at peptide bond 77, resulting in the production of C4a (M.W. 8740) and C4b fragments (M.W. 193,000). The released C4a peptide is one of the three complement-derived anaphylatoxins. The nascent C4b fragment can form a covalent ester bond with target surfaces. This covalent attachment of C4b to target acceptors is required for continuation of activation via classical pathway.

Janatova, J. 1983. Ann. N.Y. Acad. Sci. 421, 218.
Hammer, C.H., et al. 1981. J. Biol. Chem. 256, 3995.

Please refer to vial label for lot-specific concentration.

CALBIOCHEM is a registered trademark of Merck KGaA, Darmstadt, Germany