Abstract
Transport of proteins and RNA into and out of the cell nucleus is mediated largely by a family of RanGTP-binding transport receptors. Export receptors (exportins) need to bind RanGTP for efficient loading of their export cargo. We have identified eukaryotic elongation factor 1A (eEF1A) and tRNA as RanGTP-dependent binding partners of exportin-5 (Exp5). Exp5 stimulates nuclear export of eEF1A when microinjected into the nucleus of Xenopus laevis oocytes. Surprisingly, the interaction between eEF1A and Exp5 is dependent on tRNA that can interact directly with Exp5 and, if aminoacylated, recruits eEF1A into the export complex. These data suggested to us that Exp5 might support tRNA export. Indeed, not only the canonical tRNA export receptor, exportin-t, but also Exp5 can drive nuclear export of tRNA. Taken together, we show that there exists an alternative tRNA export pathway which can be exploited to keep eEF1A out of the cell nucleus.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Active Transport, Cell Nucleus / physiology*
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Amino Acid Sequence
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Animals
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Biological Transport
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Cell Nucleus / metabolism*
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Cells, Cultured
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Cloning, Molecular
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Cytoplasm / metabolism*
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Eukaryotic Initiation Factors / metabolism
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Expressed Sequence Tags
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Guanosine Triphosphate / metabolism*
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HeLa Cells
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Humans
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Karyopherins / genetics
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Karyopherins / physiology*
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Macromolecular Substances
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Mice
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Microinjections
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Molecular Sequence Data
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Oocytes
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Peptide Elongation Factor 1 / metabolism*
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Protein Interaction Mapping
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RNA, Transfer, Amino Acyl / metabolism*
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Recombinant Fusion Proteins / physiology
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Xenopus laevis
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ran GTP-Binding Protein / metabolism*
Substances
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Eukaryotic Initiation Factors
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Karyopherins
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Macromolecular Substances
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Peptide Elongation Factor 1
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RNA, Transfer, Amino Acyl
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Recombinant Fusion Proteins
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XPO5 protein, human
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Xpo5 protein, mouse
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Guanosine Triphosphate
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ran GTP-Binding Protein