Abstract
The SR proteins, a group of abundant arginine/serine (RS)-rich proteins, are essential pre-mRNA splicing factors that are localized in the nucleus. The RS domain of these proteins serves as a nuclear localization signal. We found that RS domain-bearing proteins do not utilize any of the known nuclear import receptors and identified a novel nuclear import receptor specific for SR proteins. The SR protein import receptor, termed transportin-SR (TRN-SR), binds specifically and directly to the RS domains of ASF/SF2 and SC35 as well as several other SR proteins. The nuclear transport regulator RanGTP abolishes this interaction. Recombinant TRN-SR mediates nuclear import of RS domain- bearing proteins in vitro. TRN-SR has amino acid sequence similarity to several members of the importin beta/transportin family. These findings strongly suggest that TRN-SR is a nuclear import receptor for the SR protein family.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Sequence
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Arginine / metabolism*
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Binding, Competitive
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Cell Nucleus / metabolism
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Cloning, Molecular
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HeLa Cells
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Humans
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Karyopherins
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Molecular Sequence Data
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Molecular Weight
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Nuclear Localization Signals / physiology*
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Nuclear Proteins / biosynthesis
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Nuclear Proteins / chemistry
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Nuclear Proteins / genetics
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Nuclear Proteins / metabolism*
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Peptide Fragments / biosynthesis
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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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RNA-Binding Proteins
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Receptors, Cytoplasmic and Nuclear / biosynthesis
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Receptors, Cytoplasmic and Nuclear / chemistry
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Receptors, Cytoplasmic and Nuclear / genetics
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Receptors, Cytoplasmic and Nuclear / metabolism*
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Recombinant Proteins / biosynthesis
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Recombinant Proteins / chemistry
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Recombinant Proteins / metabolism
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Ribonucleoproteins*
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Sequence Homology, Amino Acid
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Serine / metabolism*
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Serine-Arginine Splicing Factors
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beta Karyopherins*
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ran GTP-Binding Protein
Substances
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Karyopherins
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Nuclear Localization Signals
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Nuclear Proteins
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Peptide Fragments
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RNA-Binding Proteins
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Receptors, Cytoplasmic and Nuclear
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Recombinant Proteins
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Ribonucleoproteins
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beta Karyopherins
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transportin SR
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SRSF2 protein, human
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Serine-Arginine Splicing Factors
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Serine
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Arginine
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ran GTP-Binding Protein