title: Functional regulation of immunoproteasomes and transporter associated with antigen processing.
abstract: The central event in the cellular immune response to invading pathogens is the presentation of non-self antigenic peptides by major histocompatibility complex (MHC) class I molecules to cytotoxic T lymphocytes (CTLs). As peptide binding and transport proteins, MHC class I molecules have evolved distinct biochemical and cellular strategies for acquiring antigenic peptides, providing CTLs an extracellular representation of the intracellular antigen content. Whereas efficient generation of MHC class I binding peptides depends on the intracellular, immunoproteasome-mediated proteolysis machinery, translocation of peptides into the lumen of the endoplasmic reticulum requires the endoplasmic reticulum-resident, adenosine 5'-triphosphate (ATP) binding cassette transporter associated with antigen processing (TAP). Here we show, for the first time, that immunoproteasomes, TAP complexes, and MHC class I molecules are physically associated, providing an effective means of transporting MHC class I binding peptides from their sites of generation into the lumen of the endoplasmic reticulum for loading onto MHC class I molecules. In this review, we assess the current understanding of the functional regulation of immunoproteasomes and transporter associated with antigen processing.
authors.affiliation: The R. W. Johnson Pharmaceutical Research Institute, San Diego, CA 92121, USA.
authors.forename: L Y
authors.initials: LY
authors.lastname: Hwang
authors.forename: P T
authors.initials: PT
authors.lastname: Lieu
authors.forename: P A
authors.initials: PA
authors.lastname: Peterson
authors.forename: Y
authors.initials: Y
authors.lastname: Yang
mesh_terms: D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D018528:ATP-Binding Cassette Transporters / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D000818:Animals; D017951:Antigen Presentation; D001693:Biological Transport, Active; D003546:Cysteine Endopeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000276:immunology; D015395:Histocompatibility Antigens Class I / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D008954:Models, Biological; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000276:immunology; D009097:Multienzyme Complexes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology
chemical_list: D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D018528:ATP-Binding Cassette Transporters; D015395:Histocompatibility Antigens Class I; D018832:Molecular Chaperones; D009097:Multienzyme Complexes; D011948:Receptors, Antigen, T-Cell; C073119:TAP1 protein, human; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex