Residues crucial for Ras interaction with GDP-GTP exchangers.
Cdc25 is essential for Ras-mediated activation of adenylyl cyclase in the yeast Saccharomyces cerevisiae. This protein acts by catalyzing GDP-GTP exchange on yeast Ras. Harvey (Ha) ras expressed in S. cerevisiae is also recognized by both Cdc25 and Sdc25, a yeast homolog of Cdc25. Thus it is feasible to examine molecular aspects of mammalian Ras modulation by Cdc25 using the RAS/cAMP pathway in yeast as a model system. Here, we describe mutational analysis of Ha-ras for the identification of residues critical for the ability of Ras to interact with Cdc25 and related guanine nucleotide-release proteins. Mutations within codons 97-108 impaired Ras-mediated activation of adenylyl cyclase in the presence but not in the absence of mammalian GTPase-activating protein. Such mutations, therefore, affected the ability of Ras to undergo GDP-GTP exchange catalyzed by the guanine nucleotide exchanger without preventing Ras activation of the effector. Similar mutations were previously shown to impair the ability of c-ras to transform mammalian cells while having a less drastic effect on v-ras.
Segal
M
M
Department of Biological Chemistry, Alexander Silberman Institute of Life Sciences, Hebrew University, Jerusalem, Israel.
Willumsen
B M
BM
Levitzki
A
A
D000262:Adenylyl Cyclases / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D018797:Cell Cycle Proteins; D002462:Cell Membrane / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D020690:GTPase-Activating Proteins; D011905:Genes, ras; D006150:Guanine Nucleotides / Q000494:pharmacology; D006153:Guanosine Diphosphate / Q000378:metabolism*; D008969:Molecular Sequence Data; D010957:Plasmids; D011506:Proteins / Q000378:metabolism*; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D014170:Transformation, Genetic; D020668:rap GTP-Binding Proteins; D020703:ras GTPase-Activating Proteins; D020666:ras-GRF1
C542351:CDC25 protein, S cerevisiae; D018797:Cell Cycle Proteins; D005656:Fungal Proteins; D020690:GTPase-Activating Proteins; D006150:Guanine Nucleotides; D011506:Proteins; D029701:Saccharomyces cerevisiae Proteins; D020703:ras GTPase-Activating Proteins; D020666:ras-GRF1; D006153:Guanosine Diphosphate; D019204:GTP-Binding Proteins; D016283:Proto-Oncogene Proteins p21(ras); D020668:rap GTP-Binding Proteins; D000262:Adenylyl Cyclases