title: Disulfide bridges in human complement component C3b.
abstract: The disulfide bridges of human complement component C3b, derived from C3 by removal of the 77-residue C3a, have been determined. The 10 bridges are Cys537-Cys794, Cys605-Cys640, Cys851-Cys1491, Cys1079-Cys1136, Cys1336-Cys1467, Cys1367-Cys1436, Cys1484-Cys1489, Cys1496-Cys1568, Cys1515-Cys1639, and Cys1615-Cys1624. Including the 3 bridges in C3a (Cys670-Cys698, Cys672-Cys705, and Cys685-Cys706) previously determined by high-resolution X-ray crystallography [Hoppe-Seyler's Z. Physiol. Chem. 361 (1980) 1389-1399] all disulfide bridges of C3 are localized. C3 and the strongly related C4 and C5 are members of the alpha 2-macroglobulin superfamily. The predicted bridge patterns of C4 and C5 are discussed and compared with that of alpha 2-macroglobulin.
authors.affiliation: Department of Molecular Biology, University of Aarhus, Denmark.
authors.forename: K
authors.initials: K
authors.lastname: Dolmer
authors.forename: L
authors.initials: L
authors.lastname: Sottrup-Jensen
mesh_terms: D000595:Amino Acid Sequence; D003179:Complement C3b / Q000737:chemistry*; D003181:Complement C4 / Q000737:chemistry; D003182:Complement C5 / Q000737:chemistry; D004220:Disulfides; D006801:Humans; D008969:Molecular Sequence Data
chemical_list: D003181:Complement C4; D003182:Complement C5; D004220:Disulfides; D003179:Complement C3b