C4b binds to cell surface

Stable Identifier
R-HSA-981713
Type
Reaction [binding]
Species
Homo sapiens
Compartment
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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
7391573 Interaction between the labile binding sites of the fourth (C4) and fifth (C5) human complement proteins and erythrocyte cell membranes

Law, SK, Lichtenberg, NA, Holcombe, FH, Levine, RP

J Immunol 1980
8538770 The reaction mechanism of the internal thioester in the human complement component C4

Dodds, AW, Ren, XD, Willis, AC, Law, SK

Nature 1996
Participants
Participant Of
Orthologous Events
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