title: Recombinant SEC14-like proteins (TAP) possess GTPase activity.
abstract: The three human SEC14-like proteins TAP1, TAP2, and TAP3 were expressed in Escherichia coli and purified by means of an amino-terminal His-tag. The recombinant TAP proteins bound alpha-, beta-, gamma-, and delta-tocopherol, certain phospholipids, and squalene. Intriguingly, the TAP proteins showed considerable GTPase activity that was comparable to that of small GTP-binding proteins of the Rab family. Although the TAP proteins contain important motifs to provide GTPase activity, the surrounding secondary structure markedly differed from common G-protein domains. However, these motifs are located in close proximity in the TAP structure and may therefore form an active site for GTP-binding and hydrolysis.
authors.affiliation: Institute of Biochemistry and Molecular Biology, University of Bern, Bühlstrasse 28, 3012 Bern, Switzerland.
authors.forename: Daniel
authors.initials: D
authors.lastname: Habermehl
authors.forename: Petra
authors.initials: P
authors.lastname: Kempna
authors.forename: Angelo
authors.initials: A
authors.lastname: Azzi
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Zingg
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; D000595:Amino Acid Sequence; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004789:Enzyme Activation; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D020558:GTP Phosphohydrolases / Q000737:chemistry*; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D011498:Protein Precursors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
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; D002352:Carrier Proteins; D010446:Peptide Fragments; D011498:Protein Precursors; D011994:Recombinant Proteins; C100642:SEC14L1 protein, human; C073119:TAP1 protein, human; C405036:thyrotropin-releasing hormone-associated peptide 3, human; C071692:TAP2 protein, human; D020558:GTP Phosphohydrolases