title: RHP is antigenically related to factor H and binds to the globular heads of C1q.
abstract: RHP was purified from normal serum by sequential euglobin precipitation, ion exchange chromatography on DEAE-Sephacel and gel filtration using Sephacryl S-300. RHP reacted with anti-Factor H antibodies in ELISA assays and in Western blots, suggesting that it is antigenically related to Factor H. It bound to intact C1q but not to the collagen-like N-terminal half of the molecule. C1q-specific monoclonal antibody BUS-1, which blocks the binding of C1q to immune complexes, did not block the binding of RHP to C1q. This implies that the binding sites on C1q for IgG and RHP do not overlap.
authors.affiliation: Department of Biochemistry, University of Sydney, NSW, Australia.
authors.forename: S B
authors.initials: SB
authors.lastname: Easterbrook-Smith
authors.forename: M R
authors.initials: MR
authors.lastname: Wilson
authors.forename: B D
authors.initials: BD
authors.lastname: Wines
mesh_terms: D001665:Binding Sites; D001798:Blood Proteins / Q000276:immunology* / Q000302:isolation & purification; D015153:Blotting, Western; D002850:Chromatography, Gel; D003166:Complement Activating Enzymes / Q000276:immunology*; D015922:Complement C1q / Q000378:metabolism*; D003180:Complement C3b Inactivator Proteins / Q000276:immunology*; D017242:Complement Factor H; D003429:Cross Reactions; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000378:metabolism; D007074:Immunoglobulin G / Q000378:metabolism
chemical_list: D001798:Blood Proteins; C493495:CFH protein, human; D003180:Complement C3b Inactivator Proteins; D007140:Immunoglobulin Fab Fragments; D007074:Immunoglobulin G; C045510:RHP protein, human; D015922:Complement C1q; D017242:Complement Factor H; D003166:Complement Activating Enzymes