Abstract
MTR10, previously shown to be involved in mRNA export, was found in a synthetic lethal relationship with nucleoporin NUP85. Green fluorescent protein (GFP)-tagged Mtr10p localizes preferentially inside the nucleus, but a nuclear pore and cytoplasmic distribution is also evident. Purified Mtr10p forms a complex with Npl3p, an RNA-binding protein that shuttles in and out of the nucleus. In mtr10 mutants, nuclear uptake of Npl3p is strongly impaired at the restrictive temperature, while import of a classic nuclear localization signal (NLS)-containing protein is not. Accordingly, the NLS within Npl3p is extended and consists of the RGG box plus a short and non-repetitive C-terminal tail. Mtr10p interacts in vitro with Gsp1p-GTP, but with low affinity. Interestingly, Npl3p dissociates from Mtr10p only by incubation with Ran-GTP plus RNA. This suggests that Npl3p follows a distinct nuclear import pathway and that intranuclear release from its specific import receptor Mtr10p requires the cooperative action of both Ran-GTP and newly synthesized mRNA.
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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Biological Transport
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Cell Nucleus / metabolism
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Fungal Proteins / genetics
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Fungal Proteins / metabolism*
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GTP-Binding Proteins / metabolism
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Green Fluorescent Proteins
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Guanosine Triphosphate / metabolism
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Humans
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Luminescent Proteins / genetics
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Luminescent Proteins / metabolism
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Molecular Sequence Data
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Monomeric GTP-Binding Proteins*
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Mutagenesis
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Nuclear Envelope
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Nuclear Pore Complex Proteins*
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Nuclear Proteins / genetics
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Nuclear Proteins / metabolism*
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Nucleocytoplasmic Transport Proteins*
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Porins / genetics
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Porins / metabolism
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RNA, Messenger
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RNA-Binding Proteins / genetics
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RNA-Binding Proteins / metabolism*
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Ribonucleoproteins / metabolism
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Saccharomyces cerevisiae Proteins*
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Temperature
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ran GTP-Binding Protein
Substances
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Fungal Proteins
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GSP1 protein, S cerevisiae
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Luminescent Proteins
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MTR10 protein, S cerevisiae
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NPL3 protein, S cerevisiae
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NUP85 protein, S cerevisiae
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Nuclear Pore Complex Proteins
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Nuclear Proteins
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Nucleocytoplasmic Transport Proteins
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Porins
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RNA, Messenger
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RNA-Binding Proteins
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Ribonucleoproteins
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Saccharomyces cerevisiae Proteins
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Green Fluorescent Proteins
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Guanosine Triphosphate
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GTP-Binding Proteins
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Monomeric GTP-Binding Proteins
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ran GTP-Binding Protein