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

• Published in: The Journal of biological chemistry 1994-09, Vol.269 (35), p.22276-22281
• Main Authors: Wang, H, Capps, G G, Robinson, B E, Zúñiga, M C
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Antigen-Antibody Complex; beta 2-Microglobulin - metabolism; Cell Line; Disulfides - metabolism; H-2 Antigens - biosynthesis; Histocompatibility Antigen H-2D; Humans; Kinetics; Mice; Molecular Sequence Data; Protein Binding; Protein Folding; Tumor Cells, Cultured
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(17)31787-8

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.