A small ubiquitin-related polypeptide involved in targeting RanGAP1 to nuclear pore complex protein RanBP2.
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.
Mahajan
R
R
Department of Cell Biology, The Scripps Research Institute, La Jolla, California 92037, USA.
Delphin
C
C
Guan
T
T
Gerace
L
L
Melchior
F
F
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001692:Biological Transport; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins / Q000378:metabolism*; D020690:GTPase-Activating Proteins; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009685:Nuclear Envelope / Q000737:chemistry / Q000378:metabolism; D028861:Nuclear Pore Complex Proteins; D009687:Nuclear Proteins / Q000378:metabolism*; D051381:Rats; D025842:SUMO-1 Protein; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014452:Ubiquitins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D020690:GTPase-Activating Proteins; D018832:Molecular Chaperones; D028861:Nuclear Pore Complex Proteins; D009687:Nuclear Proteins; C092317:RANGAP1 protein, human; D025842:SUMO-1 Protein; D014452:Ubiquitins; C094493:ran-binding protein 2