title: Impaired transporter associated with antigen processing (TAP) function attributable to a single amino acid alteration in the peptide TAP subunit TAP1.
abstract: The heterodimeric peptide transporter TAP belongs to the ABC transporter family. Sequence comparisons with the P-glycoprotein and cystic fibrosis transmembrane conductance regulator and the functional properties of selective amino acids in these ABC transporters postulated that the glutamic acid at position 263 and the phenylalanine at position 265 of the TAP1 subunit could affect peptide transporter function. To define the role of both amino acids, TAP1 mutants containing a deletion or a substitution to alanine at position 263 or 265 were generated and stably expressed in murine and human TAP1(-/-) cells. The different TAP1 mutants were characterized in terms of expression and function of TAP, MHC class I surface expression, immune recognition, and species-specific differences. The phenotype of murine and human cells expressing human TAP1 mutants with a deletion or substitution of Glu(263) was comparable to that of TAP1(-/-) cells. In contrast, murine and human TAP1 mutant cells containing a deletion or mutation of Phe(265) of the TAP1 subunit exhibit wild-type TAP function. This was associated with high levels of MHC class I surface expression and recognition by specific CTL, which was comparable to that of wild-type TAP1-transfected control cells. Thus, biochemical and functional evidence is presented that the Glu(263) of the TAP1 protein, but not the Phe(265), is critical for proper TAP function.
authors.affiliation: Third Department of Internal Medicine, Johannes Gutenberg-University, Mainz, Germany.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Ritz
authors.forename: Ingo
authors.initials: I
authors.lastname: Drexler
authors.forename: Dirk
authors.initials: D
authors.lastname: Sutter
authors.forename: Rupert
authors.initials: R
authors.lastname: Abele
authors.forename: Christoph
authors.initials: C
authors.lastname: Huber
authors.forename: Barbara
authors.initials: B
authors.lastname: Seliger
mesh_terms: D016475:3T3 Cells; D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D000071450:ATP Binding Cassette Transporter, Subfamily B, Member 3; D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D000255:Adenosine Triphosphate / Q000378:metabolism; D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D017951:Antigen Presentation / Q000235:genetics; D002460:Cell Line; D003602:Cytotoxicity, Immunologic / Q000235:genetics; D004721:Endoplasmic Reticulum / Q000378:metabolism; D018698:Glutamic Acid / Q000235:genetics; D015395:Histocompatibility Antigens Class I / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism; D046911:Macromolecular Substances; D051379:Mice; D008810:Mice, Inbred C57BL; D016297:Mutagenesis, Site-Directed; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D010649:Phenylalanine / Q000235:genetics; D011485:Protein Binding / Q000235:genetics / Q000276:immunology; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D016415:Sequence Alignment; D017384:Sequence Deletion; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; 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; D015395:Histocompatibility Antigens Class I; D046911:Macromolecular Substances; D010446:Peptide Fragments; D021122:Protein Subunits; C073119:TAP1 protein, human; C486171:Tap1 protein, mouse; C489516:Tap2 protein, mouse; C071692:TAP2 protein, human; D018698:Glutamic Acid; D010649:Phenylalanine; D000255:Adenosine Triphosphate