title: Beta 2-microglobulin induces a conformational change in an MHC class I H chain that occurs intracellularly and is maintained at the cell surface.
abstract: beta 2-microglobulin (beta 2-m) can regulate the cell surface conformation and expression of a class I MHC H chain. To further determine how the intracellular association of beta 2-m with a class I H chain influences the subsequent cell surface conformation and expression of the H chain, we examined the expression of HLA-A3 H chains in transgenic mice. We found that the overall conformation and level of expression of a transgenic HLA-A3 H chain is determined by its previous intracellular association with beta 2-m during its maturation in the endoplasmic reticulum, and that this conformation is not altered appreciably after the H chain reaches the cell surface. This conclusion is based on two observations. First, the conformation-dependent W6/32 mAb reacts with an HLA-A3 H chain bound to human beta 2-m (h beta 2-m) on the surface of lymphocytes from (A3 x h beta 2-m)F1 double transgenic mice in which the two chains associate intracellularly after synthesis and are then co-transported to the surface membrane. Second, this W6/32 mAb does not react with an HLA-A3 H chain/h beta 2-m surface complex formed by the exchange of H chain bound mouse beta 2-m for exogenously added h beta 2-m on lymphocytes from A3 single transgenic mice in which the HLA-A3 H chain is synthesized and transported to the cell surface in association with mouse beta 2-m.
authors.affiliation: Banting and Best Department of Medical Research, University of Toronto, Ontario, Canada.
authors.forename: U G
authors.initials: UG
authors.lastname: Danliczyk
authors.forename: T L
authors.initials: TL
authors.lastname: Delovitch
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002462:Cell Membrane / Q000648:ultrastructure; D015791:HLA-A3 Antigen / Q000737:chemistry* / Q000378:metabolism; D006389:Hemagglutinins, Viral / Q000737:chemistry; D008562:Membrane Glycoproteins / Q000737:chemistry; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D017510:Protein Folding; D001613:beta 2-Microglobulin / Q000737:chemistry*
chemical_list: D015791:HLA-A3 Antigen; D006389:Hemagglutinins, Viral; D008562:Membrane Glycoproteins; D010455:Peptides; D001613:beta 2-Microglobulin