title: Major histocompatibility complex class I molecules interact with both subunits of the transporter associated with antigen processing, TAP1 and TAP2.
abstract: Prior to loading antigenic peptides, assembled major histocompatibility complex (MHC) class I molecules associate with the transporter associated with antigen processing (TAP) in a complex which also includes calreticulin and a recently described component, tapasin. The interaction of MHC class I molecules has been characterized as occurring exclusively with the TAP1 chain of the TAP heterodimer. In contrast, as described here, in the TAP-deficient human cell line T2, MHC class I molecules interact with a transfected rat TAP2 polypeptide in addition to rat TAP1. Furthermore, this interaction with TAP2 also involves calreticulin and tapasin. An association with both TAP polypeptides would presumably further enhance the efficiency of peptide loading of MHC class I molecules by allowing more than one MHC class I allele proximity to the site of peptide supply on each TAP complex.
authors.affiliation: Department of Biochemistry, University of Dundee, Scotland. sjpowis@bad.dundee.ac.uk
authors.forename: S J
authors.initials: SJ
authors.lastname: Powis
mesh_terms: D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D000071450:ATP Binding Cassette Transporter, Subfamily B, Member 3; D018528:ATP-Binding Cassette Transporters / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D017920:Antiporters / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000378:metabolism; D037282:Calreticulin; D002460:Cell Line; D015789:HLA-A2 Antigen / Q000378:metabolism*; D015235:HLA-B Antigens / Q000378:metabolism*; D059949:HLA-B51 Antigen; D006801:Humans; D007136:Immunoglobulins / Q000378:metabolism; D046911:Macromolecular Substances; D026901:Membrane Transport Proteins; D011485:Protein Binding; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012261:Ribonucleoproteins / Q000378:metabolism; D013601:T-Lymphocytes / Q000378:metabolism; D014162:Transfection
chemical_list: D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D000071450:ATP Binding Cassette Transporter, Subfamily B, Member 3; D018528:ATP-Binding Cassette Transporters; D017920:Antiporters; D002135:Calcium-Binding Proteins; D037282:Calreticulin; D015789:HLA-A2 Antigen; D015235:HLA-B Antigens; D059949:HLA-B51 Antigen; D007136:Immunoglobulins; D046911:Macromolecular Substances; D026901:Membrane Transport Proteins; D011993:Recombinant Fusion Proteins; D012261:Ribonucleoproteins; C073119:TAP1 protein, human; C486172:Tap1 protein, rat; C489514:Tap2 protein, rat; C107762:tapasin; C071692:TAP2 protein, human