title: Complement component C1r mediated cleavage of the heavy chain of the major histocompatibility class I antigens.
abstract: Apart from cleaving C1s, we demonstrate for the first time that: 1) at concentrations found in serum, the activated forms of the complement components C1r in addition to C1s can cleave the heavy chain of MHC class I antigens, 2) the cleavage by C1r and C1s is seemingly dependent upon a native configuration of the MHC class I antigen, since heat denaturation of the HLA antigens reduce the cleavage. The proteolytic fragments following C1 cleavage were characterized by precipitation with Con A-Sepharose, anti-MHC class I and anti-beta 2-microglobulin antibodies. The proteolysis of the alpha-chain of MHC class I was shown to take place between the alpha 2- and alpha 3- domains as estimated by the Con A-Sepharose precipitation pattern on SDS-PAGE. The alpha 1/alpha 2 fragment was still shown to interact with beta 2-microglobulin as shown by immunoprecipitation.
authors.affiliation: Department of Biotechnology, Lund University, Sweden.
authors.forename: H
authors.initials: H
authors.lastname: Eriksson
authors.forename: M H
authors.initials: MH
authors.lastname: Nissen
mesh_terms: D000911:Antibodies, Monoclonal; D002460:Cell Line; D015923:Complement C1r / Q000378:metabolism*; D003173:Complement C1s / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D006031:Glycosylation; D015395:Histocompatibility Antigens Class I / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D006358:Hot Temperature; D006801:Humans; D007163:Immunosorbent Techniques; D008970:Molecular Weight; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D011489:Protein Denaturation; D013329:Structure-Activity Relationship
chemical_list: D000911:Antibodies, Monoclonal; D015395:Histocompatibility Antigens Class I; D010446:Peptide Fragments; D015923:Complement C1r; D003173:Complement C1s