title: Structure of the ABC ATPase domain of human TAP1, the transporter associated with antigen processing.
abstract: The transporter associated with antigen processing (TAP) is an ABC transporter formed of two subunits, TAP1 and TAP2, each of which has an N-terminal membrane-spanning domain and a C-terminal ABC ATPase domain. We report the structure of the C-terminal ABC ATPase domain of TAP1 (cTAP1) bound to ADP. cTAP1 forms an L-shaped molecule with two domains, a RecA-like domain and a small alpha-helical domain. The diphosphate group of ADP interacts with the P-loop as expected. Residues thought to be involved in gamma-phosphate binding and hydrolysis show flexibility in the ADP-bound state as evidenced by their high B-factors. Comparisons of cTAP1 with other ABC ATPases from the ABC transporter family as well as ABC ATPases involved in DNA maintenance and repair reveal key regions and residues specific to each family. Three ATPase subfamilies are identified which have distinct adenosine recognition motifs, as well as distinct subdomains that may be specific to the different functions of each subfamily. Differences between TAP1 and TAP2 in the nucleotide-binding site may be related to the observed asymmetry during peptide transport.
authors.affiliation: Department of Molecular and Cellular Biology, Howard Hughes Medical Institute, Harvard University, 7 Divinity Avenue, Cambridge, MA 02138, USA.
authors.forename: R
authors.initials: R
authors.lastname: Gaudet
authors.forename: D C
authors.initials: DC
authors.lastname: Wiley
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*; D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000378:metabolism; D000595:Amino Acid Sequence; D001419:Bacteria / Q000378:metabolism; D001665:Binding Sites; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray; D006801:Humans; D008285:Major Histocompatibility Complex; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D021122:Protein Subunits; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
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; D021122:Protein Subunits; D011994:Recombinant Proteins; C073119:TAP1 protein, human; C071692:TAP2 protein, human; D000251:Adenosine Triphosphatases