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.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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ATP Binding Cassette Transporter, Subfamily B, Member 2
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ATP Binding Cassette Transporter, Subfamily B, Member 3
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ATP-Binding Cassette Transporters / chemistry*
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ATP-Binding Cassette Transporters / genetics
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ATP-Binding Cassette Transporters / metabolism
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Amino Acid Sequence
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Binding Sites
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Carrier Proteins / chemistry*
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Carrier Proteins / genetics
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Carrier Proteins / metabolism
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Enzyme Activation
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Escherichia coli / enzymology
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Escherichia coli / genetics
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GTP Phosphohydrolases / chemistry*
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Humans
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Models, Molecular*
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Molecular Sequence Data
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Peptide Fragments / chemistry*
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Peptide Fragments / genetics
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Peptide Fragments / metabolism
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Protein Binding
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Protein Precursors / chemistry*
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Protein Precursors / genetics
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Protein Precursors / metabolism
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Recombinant Proteins / analysis
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Recombinant Proteins / chemistry*
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Recombinant Proteins / metabolism
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Sequence Homology, Amino Acid
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Structure-Activity Relationship
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Substrate Specificity
Substances
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ATP Binding Cassette Transporter, Subfamily B, Member 2
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ATP Binding Cassette Transporter, Subfamily B, Member 3
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ATP-Binding Cassette Transporters
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Carrier Proteins
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Peptide Fragments
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Protein Precursors
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Recombinant Proteins
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SEC14L1 protein, human
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TAP1 protein, human
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thyrotropin-releasing hormone-associated peptide 3, human
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TAP2 protein, human
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GTP Phosphohydrolases