Abstract
Eukaryotic initiation factor 5A (eIF-5A) is the only cellular protein known to contain the unusual amino acid hypusine. The exact in vivo function of eIF-5A, however, is to date unknown. The finding that eIF-5A is an essential cofactor of the human immunodeficiency virus type 1 (HIV-1) Rev RNA transport factor suggested that eIF-5A is part of a specific nuclear export pathway. In this study we used indirect immunofluorescence and immunogold electron microscopy to demonstrate that eIF-5A accumulates at nuclear pore-associated intranuclear filaments in mammalian cells and Xenopus oocytes. We are able to show that eIF-5A interacts with the general nuclear export receptor, CRM1. Furthermore, microinjection studies in somatic cells revealed that eIF-5A is transported from the nucleus to the cytoplasm, and that this nuclear export is blocked by leptomycin B. Our data demonstrate that eIF-5A is a nucleocytoplasmic shuttle protein.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Animals
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Base Sequence
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Biological Transport, Active / drug effects
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Carrier Proteins / metabolism*
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Cytoplasm / metabolism
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DNA Primers / genetics
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Eukaryotic Translation Initiation Factor 5A
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Exportin 1 Protein
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Fatty Acids, Unsaturated / pharmacology
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Female
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Fluorescent Antibody Technique, Indirect
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Humans
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In Vitro Techniques
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Karyopherins*
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Microscopy, Immunoelectron
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Nuclear Envelope / metabolism*
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Oocytes / metabolism
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Peptide Initiation Factors / chemistry
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Peptide Initiation Factors / genetics
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Peptide Initiation Factors / metabolism*
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RNA-Binding Proteins*
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Receptors, Cytoplasmic and Nuclear*
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Recombinant Fusion Proteins / chemistry
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Xenopus laevis
Substances
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Carrier Proteins
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DNA Primers
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Fatty Acids, Unsaturated
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Karyopherins
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Peptide Initiation Factors
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RNA-Binding Proteins
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Receptors, Cytoplasmic and Nuclear
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Recombinant Fusion Proteins
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leptomycin B