C4b-binding protein

complement component 4 binding protein, beta
complement component 4 binding protein, beta
Identifiers
Symbol	C4BPB
Alt. symbols	C4BP
NCBI gene	725
HGNC	1328
OMIM	120831
RefSeq	NM_000716
UniProt	P20851
Other data
Locus	Chr. 1 q32
Structures
Search for
Structures	Swiss-model
Domains	InterPro

Search for
Structures	Swiss-model
Domains	InterPro

complement component 4 binding protein, alpha
complement component 4 binding protein, alpha
Identifiers
Symbol	C4BPA
Alt. symbols	C4BP
NCBI gene	722
HGNC	1325
OMIM	120830
PDB	4B0F
RefSeq	NM_000715
UniProt	P04003
Other data
Locus	Chr. 1 q32
Structures
Search for
Structures	Swiss-model
Domains	InterPro

C4b-binding protein (C4BP) is a protein complex involved in the complement system where it acts as inhibitor. C4BP has an octopus-like structure with a central stalk and seven branching alpha-chains. The main form of C4BP in human blood is composed of 7 identical alpha-chains and one unique beta-chain, which in turn binds anticoagulant, vitamin K-dependent protein S.

C4BP is a large glycoprotein (500 kDa) with an estimated plasma concentration of 200 micrograms/mL synthesized mainly in the liver.

The genes coding for C4BP α-chain (C4BPA) and β-chain (C4BPB) are located in the regulators of complement activation (RCA) gene cluster on the long arm of chromosome 1 in the vicinity of other complement inhibitors.