Complement C4 (beta chain) Rabbit Polyclonal Antibody

Function

Complement component C4 is an essential component of humoral immune response. C4 plays a central role in the activation of the classical pathway of the complement system. It is processed by activated C1 which removes from the alpha chain the C4a anaphylatoxin. The remaining alpha chain fragment C4b is the major activation product and is an essential subunit of the C3 convertase (C4b2a) and the C5 convertase (C3bC4b2a) enzymes of the classical complement pathway. Each C4 contains beta chain, alpha chain,C4a anaphyltoxin, C4b and gamma chain.

Background References

1. "Identification and quantification of N-linked glycoproteins using hydrazide chemistry, stable isotope labeling and mass spectrometry."Zhang H., Li X.-J., Martin D.B., Aebersold R.Nat. Biotechnol. 21: 660-666(2003)

2. "Screening for N-glycosylated proteins by liquid chromatography mass spectrometry."Bunkenborg J., Pilch B.J., Podtelejnikov A.V., Wisniewski J.R.Proteomics 4:454-465(2004)

Tissue Specificity

Complement component C4 is expressed at highest levels in the liver, at moderate levels in the adrenal cortex, adrenal medulla, thyroid gland, and the kidney, and at lowest levels in the heart, ovary, small intestine, thymus, pancreas and spleen. The extra-hepatic sites of expression may be important for the local protection and inflammatory response.

Post-translational Modification

Prior to secretion, the single-chain precursor is enzymatically cleaved to yield non-identical chains alpha, beta and gamma. During activation, the alpha chain is cleaved by C1 into C4a and C4b, and C4b stays linked to the beta and gamma chains. Further degradation of C4b by C1 into the inactive fragments C4c and C4d blocks the generation of C3 convertase. The proteolytic cleavages often are incomplete so that many structural forms can be found in plasma.; N- and O-glycosylated. O-glycosylated with a core 1 or possibly core 8 glycan.

Subcellular Location

Secreted.

UNIPROT

SwissProt: P0C0L4 Human

Synonyms