Inhibition of nuclear protein import by nonhydrolyzable analogues of GTP and identification of the small GTPase Ran/TC4 as an essential transport factor - PubMed (original) (raw)

Inhibition of nuclear protein import by nonhydrolyzable analogues of GTP and identification of the small GTPase Ran/TC4 as an essential transport factor

F Melchior et al. J Cell Biol. 1993 Dec.

Erratum in

Abstract

We have investigated a possible involvement of GTPases in nuclear protein import using an in vitro transport system involving digitonin-permeabilized cells supplemented with exogenous cytosol. Transport in this system was measured with a novel ELISA-based assay that allows rapid quantitative analysis. GTP gamma S and other nonhydrolyzable analogues of GTP were found to rapidly inhibit the rate of in vitro nuclear import. Transport inhibition by GTP gamma S was dependent on the concentrations of permeabilized cells and cytosol, and was strongly enhanced by a cytosolic factor(s). The predominant cytosolic component responsible for this inhibition was found in a 20-30-kD fraction in molecular sieving chromatography. Furthermore, a component(s) of this 20-30-kD fraction was itself required for efficient nuclear import. Biochemical complementation with bacterially expressed protein demonstrated that this essential GTP gamma S-sensitive transport factor was Ran/TC4, a previously described GTPase of the Ras superfamily found in both nucleus and cytoplasm. Ran/TC4 and its guanine nucleotide release protein RCC1 have previously been implicated in DNA replication, cell cycle checkpoint control, and RNA synthesis, processing and export. Our results suggest that Ran/TC4 serves to integrate nuclear protein import with these other nuclear activities.

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References

    1. EMBO J. 1991 Jun;10(6):1555-64 - PubMed
    1. Nature. 1992 Aug 6;358(6386):512-4 - PubMed
    1. Cell. 1991 Jul 12;66(1):15-22 - PubMed
    1. Cell. 1988 Mar 11;52(5):641-53 - PubMed
    1. J Cell Biol. 1986 Dec;103(6 Pt 1):2091-102 - PubMed

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