The Saccharomyces cerevisiae CDC25 gene product binds specifically to catalytically inactive ras proteins in vivo.
Genetic data suggest that the yeast cell cycle control gene CDC25 is an upstream regulator of RAS2. We have been able to show for the first time that the guanine nucleotide exchange proteins Cdc25 and Sdc25 from Saccharomyces cerevisiae bind directly to their targets Ras1 and Ras2 in vivo. Using the characteristics of the yeast Ace1 transcriptional activator to probe for protein-protein interaction, we found that the CDC25 gene product binds specifically to wild-type Ras2 but not to the mutated Ras2Val-19 and Ras2 delta Val-19 proteins. The binding properties of Cdc25 to Ras2 were strongly diminished in yeast cells expressing an inactive Ira1 protein, which normally acts as a negative regulator of Ras activity. On the basis of these data, we propose that the ability of Cdc25 to interact with Ras2 proteins is strongly dependent on the activation state of Ras2. Cdc25 binds predominantly to the catalytically inactive GDP-bound form of Ras2, whereas a conformational change of Ras2 to its activated GTP-bound state results in its loss of binding affinity to Cdc25.
Munder
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Department of Biotechnology, CIBA-GEIGY Ltd., Basel, Switzerland.
Fürst
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D000595:Amino Acid Sequence; D001483:Base Sequence; D018797:Cell Cycle Proteins; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism; D020690:GTPase-Activating Proteins; D005800:Genes, Fungal; D005809:Genes, Regulator; D005838:Genotype; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides; D010957:Plasmids; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism; D018631:ras Proteins; D020666:ras-GRF1
C542351:CDC25 protein, S cerevisiae; D018797:Cell Cycle Proteins; D005656:Fungal Proteins; D020690:GTPase-Activating Proteins; C065725:IRA1 protein, S cerevisiae; D009838:Oligodeoxyribonucleotides; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D020666:ras-GRF1; D001616:beta-Galactosidase; D019204:GTP-Binding Proteins; C489014:RAS1 protein, S cerevisiae; C489015:RAS2 protein, S cerevisiae; D018631:ras Proteins