Abstract
We have found that the mammalian Ran GTPase-activating protein RanGAP1 is highly concentrated at the cytoplasmic periphery of the nuclear pore complex (NPC), where it associates with the 358-kDa Ran-GTP-binding protein RanBP2. This interaction requires the ATP-dependent posttranslational conjugation of RanGAP1 with SUMO-1 (for small ubiquitin-related modifier), a novel protein of 101 amino acids that contains low but significant homology to ubiquitin. SUMO-1 appears to represent the prototype for a novel family of ubiquitin-related protein modifiers. Inhibition of nuclear protein import resulting from antibodies directed at NPC-associated RanGAP1 cannot be overcome by soluble cytosolic RanGAP1, indicating that GTP hydrolysis by Ran at RanBP2 is required for nuclear protein import.
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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3T3 Cells
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Amino Acid Sequence
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Animals
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Base Sequence
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Biological Transport
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Cell Line
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Cell Nucleus / metabolism*
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DNA, Complementary / genetics
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DNA-Binding Proteins / metabolism*
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GTPase-Activating Proteins*
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HeLa Cells
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Humans
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Mice
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Molecular Chaperones
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Molecular Sequence Data
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Molecular Weight
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Nuclear Envelope / chemistry
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Nuclear Envelope / metabolism
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Nuclear Pore Complex Proteins*
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Nuclear Proteins / metabolism*
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Rats
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SUMO-1 Protein
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Sequence Analysis, DNA
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Sequence Homology, Amino Acid
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Ubiquitins / genetics
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Ubiquitins / isolation & purification
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Ubiquitins / metabolism*
Substances
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DNA, Complementary
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DNA-Binding Proteins
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GTPase-Activating Proteins
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Molecular Chaperones
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Nuclear Pore Complex Proteins
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Nuclear Proteins
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RANGAP1 protein, human
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SUMO-1 Protein
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Ubiquitins
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ran-binding protein 2