Yrb1p interaction with the gsp1p C terminus blocks Mog1p stimulation of GTP release from Gsp1p.
Mog1p, a multicopy suppressor of gsp1, the temperature-sensitive mutant of the Saccharomyces cerevisiae Ran homologue, binds to GTP-Gsp1p but not to GDP-Gsp1p. The function of Mog1p in the Ran cycle is as yet unknown. This study found that Mog1p releases a nucleotide from GTP-Gsp1p but not from GDP-Gsp1p. Yrb1p, the S. cerevisiae homologue of RanBP1, which is a strong inhibitor of RCC1-stimulated nucleotide release, also inhibited the Mog1p-stimulated nucleotide release from GTP-Gsp1p. At a concentration corresponding to the molar concentration of GTP-Gsp1p, Yrb1p completely inhibited the Mog1p-stimulated nucleotide release. Consistently, the Yrb1p.GTP-Gsp1p complex was more stable than the Mog1p.GTP-Gsp1p complex. Yrb1p did not inhibit the Mog1p-stimulated nucleotide release from GTP-Gsp1DeltaC. The Gsp1DeltaC protein lacks the final eight amino acids of the C terminus, and for this reason, the interaction between GTP-Gsp1DeltaC and Yrb1p was strongly reduced. On the other hand, Mog1p binds to GTP-Gsp1DeltaC more efficiently than to GTP-Gsp1p.
Oki
M
M
Department of Molecular Biology, Graduate School of Medical Science, Kyushu University, Fukuoka 812-8582, Japan.
Nishimoto
T
T
D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism*; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D005656:Fungal Proteins / Q000378:metabolism; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D007700:Kinetics; D020559:Monomeric GTP-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D009687:Nuclear Proteins / Q000737:chemistry* / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins; D020931:ran GTP-Binding Protein / Q000378:metabolism*
D002352:Carrier Proteins; D005656:Fungal Proteins; C080324:GSP1 protein, S cerevisiae; D009687:Nuclear Proteins; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; C410219:MOG1 protein, S cerevisiase; D020559:Monomeric GTP-Binding Proteins; D020931:ran GTP-Binding Protein