Reactome | C4b binds to cell surface

C4b binds to cell surface

Stable Identifier

R-HSA-981713

Type

Reaction [binding]

Species

Homo sapiens

Compartment

plasma membrane, extracellular region

ReviewStatus

5/5

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The cleavage of C4 into C4a and C4b releases an acyl group from the intrachain thioester bond, allowing C4b to bond covalently to any adjacent biological substrates (Dodds & Law 1998). C4 is encoded at two loci, C4A and C4B. The C4b proteins derived from these genes are not identical and have different binding preferences (Law et al 1984, Sepp et al. 1993); C4A-derived C4b binds more efficiently than C4B-derived C4b to amino groups, while C4B-derived C4b is more effective than C4A in binding to hydroxyl groups. The site of C4b deposition is not clearly established (Møller-Kristensen et al. 2003) but generally accepted to be the activating cell membrane surface, though it may be the activating complex itself.

Literature References

PubMed ID	Title	Journal	Year
8538770	The reaction mechanism of the internal thioester in the human complement component C4 Ren, XD, Dodds, AW, Willis, AC, Law, SK	Nature	1996
7391573	Interaction between the labile binding sites of the fourth (C4) and fifth (C5) human complement proteins and erythrocyte cell membranes Levine, RP, Law, SK, Holcombe, FH, Lichtenberg, NA	J Immunol	1980