title: Reconstitution by MHC-restricted peptides of HLA-A2 heavy chain with beta 2-microglobulin, in vitro.
abstract: Cytotoxic T lymphocytes kill virally infected cells when they detect antigenic fragments presented by class I major histocompatibility complex (MHC) antigens (HLA in humans). The crystal structures of HLA-A2 and HLA-Aw68 reveal that peptide-antigen forms an integral part of the HLA structure, being retained in a prominent groove even after purification and crystallization. Here we report that the heavy chain and beta 2-microglobulin of HLA-A2, after separation and fractionation in denaturants, reassemble efficiently under renaturing conditions only in the presence of MHC-restricted peptides. A complex of heavy chain, beta 2-microglobulin, and viral peptide in the ratio 1:1:1 is formed in up to 46% yield. Reconstitution is not stimulated by either of two peptides not restricted to HLA-A2. The reconstituted complex of HLA-A2 and the influenza virus (B/Lee/40) nucleoprotein peptide, Np (85-94), crystallizes under conditions previously used to crystallize HLA-A2. Peptide-linked folding and assembly suggests mechanisms for the unusual capacity of HLA to bind many peptides of diverse sequence.
authors.affiliation: Department of Biochemistry and Molecular Biology, Harvard University, Cambridge, Massachusetts 02138.
authors.forename: M L
authors.initials: ML
authors.lastname: Silver
authors.forename: K C
authors.initials: KC
authors.lastname: Parker
authors.forename: D C
authors.initials: DC
authors.lastname: Wiley
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002850:Chromatography, Gel; D015789:HLA-A2 Antigen / Q000235:genetics; D006801:Humans; D015151:Immunoblotting; D046911:Macromolecular Substances; D008285:Major Histocompatibility Complex; D008969:Molecular Sequence Data; D009698:Nucleoproteins; D011485:Protein Binding; D001613:beta 2-Microglobulin / Q000235:genetics
chemical_list: D015789:HLA-A2 Antigen; D046911:Macromolecular Substances; D009698:Nucleoproteins; D001613:beta 2-Microglobulin