title: Disulfide bond-mediated dimerization of HLA-G on the cell surface.
abstract: HLA-G is a nonclassical class I MHC molecule with an unknown function and with unusual characteristics that distinguish it from other class I MHC molecules. Here, we demonstrate that HLA-G forms disulfide-linked dimers that are present on the cell surface. Immunoprecipitation of HLA-G from surface biotinylated transfectants using the anti-beta2-microglobulin mAb BBM.1 revealed the presence of an approximately equal 78-kDa form of HLA-G heavy chain that was reduced by using DTT to a 39-kDa form. Mutation of Cys-42 to a serine completely abrogated dimerization of HLA-G, suggesting that the disulfide linkage formed exclusively through this residue. A possible interaction between the HLA-G monomer or dimer and the KIR2DL4 receptor was also investigated, but no interaction between these molecules could be detected through several approaches. The cell-surface expression of dimerized HLA-G molecules may have implications for HLA-Greceptor interactions and for the search for specific receptors that bind HLA-G.
authors.affiliation: Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138; and Institute of Molecular Genetics, 142 20 Prague, Czech Republic.
authors.forename: Jonathan E
authors.initials: JE
authors.lastname: Boyson
authors.forename: Robert
authors.initials: R
authors.lastname: Erskine
authors.forename: Mary C
authors.initials: MC
authors.lastname: Whitman
authors.forename: Michael
authors.initials: M
authors.lastname: Chiu
authors.forename: Julie M
authors.initials: JM
authors.lastname: Lau
authors.forename: Louise A
authors.initials: LA
authors.lastname: Koopman
authors.forename: Markus M
authors.initials: MM
authors.lastname: Valter
authors.forename: Pavla
authors.initials: P
authors.lastname: Angelisova
authors.forename: Vaclav
authors.initials: V
authors.lastname: Horejsi
authors.forename: Jack L
authors.initials: JL
authors.lastname: Strominger
mesh_terms: D019943:Amino Acid Substitution; D000954:Antigens, Surface / Q000737:chemistry*; D002822:Choriocarcinoma / Q000276:immunology / Q000473:pathology; D003545:Cysteine / Q000737:chemistry; D003553:Cystine / Q000737:chemistry; D019281:Dimerization; D004229:Dithiothreitol / Q000494:pharmacology; D005260:Female; D005802:Genes, MHC Class II; D006680:HLA Antigens / Q000737:chemistry*; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I / Q000737:chemistry*; D006801:Humans; D008970:Molecular Weight; D010084:Oxidation-Reduction; D011247:Pregnancy; D025941:Protein Interaction Mapping; D011971:Receptors, Immunologic / Q000235:genetics / Q000378:metabolism; D054340:Receptors, KIR; D054345:Receptors, KIR2DL4; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D014162:Transfection; D014407:Tumor Cells, Cultured; D014594:Uterine Neoplasms / Q000276:immunology / Q000473:pathology
chemical_list: D000954:Antigens, Surface; D006680:HLA Antigens; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I; C515079:KIR2DL4 protein, human; D011971:Receptors, Immunologic; D054340:Receptors, KIR; D054345:Receptors, KIR2DL4; D011993:Recombinant Fusion Proteins; D003553:Cystine; D003545:Cysteine; D004229:Dithiothreitol