Saccharomyces cerevisiae CDC25 (1028-1589) is a guanine nucleotide releasing factor for mammalian ras proteins and is oncogenic in NIH3T3 cells.
The best characterized yeast guanine nucleotide releasing factor is CDC25, which acts on RAS and thereby stimulates cAMP production in Saccharomyces cerevisiae. In order to determine if CDC25 could be a specific GDP-GTP releasing factor for the mammalian proteins Ha-ras, Ki-ras, and N-ras, its functions were studied both in vitro and in NIH3T3 cells. The 561 amino acid composing the C-terminal domain of CDC25 (CDC25 C-domain) released guanine nucleotides (both GDP and GTP) from Ha-, Ki-, and N-ras but not from Rap1A, Rab5, and Rab11. CDC25 acted on oncogenically activated Ha-ras even if the last 23 amino acids (167-189) of the Ras proteins were not present. CDC25 transformed NIH3T3 cells; its transforming capacity was enhanced by overexpression of wild-type Ha-ras. CDC25 C-domain probably exerts its effects through the activation of cellular Ras proteins. These data suggest that the CDC25 C-domain can function as an upstream activator of Ras proteins in a heterologous system and therefore could be a useful tool to study the regulation of Ras activation by growth factor receptors.
Molecular Oncology Laboratory, CRVA-IBV, Rhône-Poulenc Rorer, Vitry sur Seine, France.
M C
MC
Chevallier-Multon
F
F
Schweighoffer
I
I
Barlat
N
N
Baudouy
I
I
Fath
M
M
Duchesne
B
B
Tocqué
D016475:3T3 Cells; D000818:Animals; D018797:Cell Cycle Proteins; D002471:Cell Transformation, Neoplastic; D004742:Enhancer Elements, Genetic; D004926:Escherichia coli / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006153:Guanosine Diphosphate / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism; D007700:Kinetics; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D010957:Plasmids; D011120:Polyomavirus / Q000235:genetics; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D014162:Transfection / Q000379:methods; D020666:ras-GRF1
C542351:CDC25 protein, S cerevisiae; D018797:Cell Cycle Proteins; D005656:Fungal Proteins; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D020666:ras-GRF1; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; D019204:GTP-Binding Proteins; D016283:Proto-Oncogene Proteins p21(ras)