RNA1 Encodes a GTPase-activating Protein Specific for Gsp1p, the Ran/TC4 Homologue of Saccharomyces cerevisiae

doi:10.1074/jbc.270.20.11860

RNA1 Encodes a GTPase-activating Protein Specific for Gsp1p, the Ran/TC4 Homologue of Saccharomyces cerevisiae(*)

From the (1) Max-Planck Institut für Molekulare Physiologie, Abteilung Strukturelle Biologie, 44139 Dortmund, Germany, the
(2) Universität Münster Zentrum für Dermatologie, 48149 Münster, Germany, the
(3) Departments of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, California 92037, and the
(4) Project Molecular Biology of Mitosis, Deutsches Krebsforschungszentrum, 69120 Heidelberg, Germany

^§To whom correspondence should be addressed:
Max-Planck-Institute für Molekulare Physiologie, Abteilung für Strukturelle Biologie, P. O. Box 10 26 64, 44026 Dortmund, Germany.
Tel.: 49-0231-1206-240; Fax: 49-0231-1206-230; E-mail: jbecker{at}mpi-dortmund.mpg.de.

Abstract

Ran/TC4 is a ras-related GTP-binding protein predominantly located in the nucleus. Ran/TC4 is essential for nuclear transport and is involved in mitotic control. In Saccharomyces cerevisiae a gene highly homologous to Ran/TC4 has been identified and named GSP1. Like all ras-related GTP-binding proteins, Gsp1p undergoes cycles of GTP hydrolysis and GDP/GTP exchange. The switching between the two different nucleotide bound states regulates the function of these GTP-binding proteins. Here we identify the product of the yeast RNA1 gene as the GTPase-activating protein (GAP) of Gsp1p. RNA1 belongs to a group of genes which are conserved in a variety of different organisms. We have expressed and purified recombinant Gsp1p and Rna1p from Escherichia coli. The GTPase activity of Gsp1p is stimulated 10⁷-fold by Rna1p. In addition, we find that the previously identified human RanGAP1 and rna1p from Schizosaccharomyces pombe are also able to induce GTPase activity of Gsp1p. The GTP hydrolysis of Ran is induced by RanGAP1 and rna1p but not by Rna1p. Implications for the suggested functions of Ran/TC4/Gsp1p in nuclear transport and mitotic control are discussed.

Footnotes

↵* The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

RCC1

regulator of chromosome condensation

Ran

ras-related nuclear protein

RanGAP1

the human GTPase-activating protein for Ran

PRP20

S. cerevisiae gene functionally homologous to RCC1 involved in precursor RNA processing

GAP

GTPase-activating protein

GEF

guanine nucleotide exchange factor

GSP1, GTP binding suppressor of PRP20

S. cerevisiae gene homologous to Ran/TC4

RNA1

S. cerevisiae gene coding for protein involved in mRNA processing and transport

LRR

leucine-rich repeats

PAGE

polyacrylamide gel electrophoreis

DTE

dithioerythritol.
↵²X. Skinner and L. Wiesmüller, unpublished data.