Requirement of Guanosine Triphosphate-Bound Ran for Signal-Mediated Nuclear Protein Export

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Science  20 Jun 1997:
Vol. 276, Issue 5320, pp. 1842-1844
DOI: 10.1126/science.276.5320.1842

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A leucine-rich nuclear export signal (NES) allows rapid export of proteins from cell nuclei. Microinjection studies revealed a role for the guanosine triphosphatase (GTPase) Ran in NES-mediated export. Nuclear injection of a Ran mutant (Thr24 → Asn) blocked protein export but not import, whereas depletion of the Ran nucleotide exchange factor RCC1 blocked protein import but not export. However, injection of Ran GTPase-activating protein (RanGAP) into RCC1-depleted cell nuclei inhibited export. Coinjection with Ran mutants insensitive to RanGAP prevented this inhibition. Therefore, NES-mediated protein export appears to require a Ran-GTP complex but does not require Ran-dependent GTP hydrolysis.

  • * Present address: Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.

  • To whom correspondence should be addressed. E-mail: igm9c{at}

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