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1: Cell. 1997 Jan 10;88(1):97-107.Click here to read Links

A small ubiquitin-related polypeptide involved in targeting RanGAP1 to nuclear pore complex protein RanBP2.

Mahajan R, Delphin C, Guan T, Gerace L, Melchior F.

Department of Cell Biology, The Scripps Research Institute, La Jolla, California 92037, USA.

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.

PMID: 9019411 [PubMed - indexed for MEDLINE]