title: Tetrameric cell-surface MHC class I molecules.
abstract: Purified major histocompatibility complex (MHC) class I molecules have been studied at high resolution by X-ray crystallography; the structure is a complex of a single heavy chain, a beta 2-microglobulin light chain and a tightly bound peptide moiety. We show here that complete MHC class I molecules are post-translationally assembled into tetramers (made up of four heavy chains and four beta 2-microglobulin units) and that this tetrameric species is expressed on the cell surface. The multivalent tetrameric structure of class I molecules can be reconciled with models of T-cell activation that invoke antigen-receptor crosslinking, as opposed to models that depend on an allosteric change.
authors.affiliation: Molecular Immunology Laboratory, Cancer Center of Massachusetts General Hospital, Boston.
authors.forename: S
authors.initials: S
authors.lastname: Krishna
authors.forename: P
authors.initials: P
authors.lastname: Benaroch
authors.forename: S
authors.initials: S
authors.lastname: Pillai
mesh_terms: D000818:Animals; D000906:Antibodies; D001345:Autoradiography; D002460:Cell Line; D002462:Cell Membrane / Q000276:immunology; D003432:Cross-Linking Reagents; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D015395:Histocompatibility Antigens Class I / Q000096:biosynthesis / Q000737:chemistry* / Q000302:isolation & purification; D008214:Lymphocytes / Q000276:immunology; D046911:Macromolecular Substances; D008715:Methionine / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D013462:Sulfur Radioisotopes
chemical_list: D000906:Antibodies; D003432:Cross-Linking Reagents; D015395:Histocompatibility Antigens Class I; D046911:Macromolecular Substances; D013462:Sulfur Radioisotopes; D008715:Methionine