title: Ab initio association with beta 2-microglobulin during biosynthesis of the H-2Ld class I major histocompatibility complex heavy chain promotes proper disulfide bond formation and stable peptide binding.
abstract: In vitro translation studies indicate that the beta 2-microglobulin (beta 2-m) light chain influences the formation of intrachain disulfide bonds in class I major histocompatibility complex (MHC) molecules during their biosynthesis. We now have examined the influence of beta 2-m on class I MHC intrachain disulfide bond formation in vivo. Using beta 2-m+ and beta 2-m- derivatives of a cell line transfected with the mouse H-2Ld gene, we show that all of the H-2Ld molecules from beta 2-m+ cells have both the alpha 2 and alpha 3 intrachain disulfide bonds, whereas about 50% of the H-2Ld molecules from beta 2-m- cells have only one of these bonds. All of the free H-2Ld heavy chains from beta 2-m+ cells can undergo a peptide-induced conformational change and can bind exogenous peptide and beta 2-m stably in vitro. Only those H-2Ld molecules from beta 2-m- cells, which have both intrachain disulfide bonds, undergo a peptide- and beta 2-m-induced conformational change in vitro. These H-2Ld molecules do not bind beta 2-m and peptide stably in vitro. From these results emerges a greater understanding of the role of beta 2-m at the time of class I MHC molecule synthesis: beta 2-m promotes intrachain disulfide bond formation in the class I MHC molecule and additionally affects class I MHC structure to render it competent to form stable trimolecular complexes with peptide and beta 2-m.
authors.affiliation: Department of Biology, Sinsheimer Laboratories, University of California, Santa Cruz 95064.
authors.forename: H
authors.initials: H
authors.lastname: Wang
authors.forename: G G
authors.initials: GG
authors.lastname: Capps
authors.forename: B E
authors.initials: BE
authors.lastname: Robinson
authors.forename: M C
authors.initials: MC
authors.lastname: Zúñiga
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000936:Antigen-Antibody Complex; D002460:Cell Line; D004220:Disulfides / Q000378:metabolism*; D006183:H-2 Antigens / Q000096:biosynthesis*; D064532:Histocompatibility Antigen H-2D; D006801:Humans; D007700:Kinetics; D051379:Mice; D008969:Molecular Sequence Data; D011485:Protein Binding; D017510:Protein Folding; D014407:Tumor Cells, Cultured; D001613:beta 2-Microglobulin / Q000378:metabolism*
chemical_list: D000936:Antigen-Antibody Complex; D004220:Disulfides; D006183:H-2 Antigens; D064532:Histocompatibility Antigen H-2D; D001613:beta 2-Microglobulin