Identification of the C3b receptor-binding domain in third component of complement.

摘要: We report here that complement receptor type one (CR1) binds to a region of C3b is contained within the NH2 terminus alpha' chain. In an enzyme-linked immunosorbent assay, CR1 bound C3b, iC3b, and C3c but not C3d, this binding was inhibited by soluble C3c. Further attempts generate small C3 fragment capable were unsuccessful. However, elastase degradation generated four species (C3c I-IV), two which CR1. NH2-terminal sequence analysis sodium dodecyl sulfate-gel electrophoresis C3cs indicated beta chains 40,000-dalton COOH-terminal chain fragments identical; I-IV varied from 21,000 27,000 daltons accounted for differential C3c-I II, do bind CR1, missing 8 9 residues when compared with intact C3b. C3c-III IV, had termini identical Using iodinated concanavalin A endoglycosidase H, we showed III glycosylated, while C3c-II IV not. Therefore, these data amino responsible COOH involved since presence or absence in did affect Subsequently, peptides synthesized C3c: X42, 42 length C30, 30 terminus. X42 effect also observed antipeptide antibodies against peptide. The C30 other C3-derived no on