Rna1p, a Ran/TC4 GTPase activating protein, is required for nuclear import - PubMed (original) (raw)

Rna1p, a Ran/TC4 GTPase activating protein, is required for nuclear import

A H Corbett et al. J Cell Biol. 1995 Sep.

Abstract

The Saccharomyces cerevisiae gene, RNA1, encodes a protein with extensive homology to the mammalian Ran/TC4 GTPase activating protein. Using indirect immunofluorescence microscopy, we have demonstrated that rna1-1 mutant cells are defective in nuclear import of several proteins. The same result is obtained when nuclear import is examined in living cells using a nuclear protein fused to the naturally green fluorescent protein. These findings suggest a role for the Rna1p in trafficking of proteins across the nuclear membrane. To investigate this role more directly, an in vitro import assay that monitors the import of a fluorescently labeled substrate into the nuclei of semi-intact yeast cells was used. Import to the nucleus requires the addition of exogenous cytosol. Results indicate that, in contrast to wild-type cytosols, extracts made from rna1-1 mutant cells are unable to support import of the fluorescently labeled substrate into competent nuclei. Immunoblotting demonstrates that these mutant-derived extracts are depleted of Rna1p. However, when purified Rna1p is added back to these extracts the import activity is restored in a dose-dependent manner. These results demonstrate that Rna1p plays a direct role in the import of proteins into the nucleus.

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References

    1. Proc Natl Acad Sci U S A. 1995 Jan 3;92(1):225-9 - PubMed
    1. Gene. 1988 Jul 15;67(1):31-40 - PubMed
    1. Cell. 1994 Dec 16;79(6):931-4 - PubMed
    1. Proc Natl Acad Sci U S A. 1994 Mar 29;91(7):2587-91 - PubMed
    1. Mol Biol Cell. 1992 Aug;3(8):875-93 - PubMed

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