The CDC25 gene product is a guanine nucleotide exchange factor for Ras proteins in yeast. Recently it has been suggested that the intracellular levels of guanine nucleotides may influence the exchange reaction. To test this hypothesis we measured the levels of nucleotides in yeast cells under different growth conditions and the relative amount of Ras2-GTP. The intracellular GTP/GDP ratio was found to be very sensitive to growth conditions: the ratio is high, close to that of ATP/ADP during exponential growth, but it decreases rapidly before the beginning of stationary phase, and it drops further under starvation conditions. The addition of glucose to glucose-starved cells causes a fast increase of the GTP/GDP ratio. The relative amount of Ras2-GTP changes in a parallel way suggesting that there is a correlation with the cytosolic GTP/GDP ratio. In addition 'in vitro' mixed-nucleotide exchange experiments done on purified Ras2 protein demonstrated that the GTP and GDP concentrations influence the extent of Ras2-GTP loading giving further support to their possible regulatory role. © 2001 Elsevier Science B.V.

Rudoni, S., Colombo, S., Coccetti, P., Martegani, E. (2001). Role of guanine nucleotides in the regulation of the Ras/cAMP pathway in Saccharomyces cerevisiae. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH, 1538(2-3), 181-189 [10.1016/S0167-4889(01)00067-2].

Role of guanine nucleotides in the regulation of the Ras/cAMP pathway in Saccharomyces cerevisiae

COLOMBO, SONIA;COCCETTI, PAOLA;MARTEGANI, ENZO
2001

Abstract

The CDC25 gene product is a guanine nucleotide exchange factor for Ras proteins in yeast. Recently it has been suggested that the intracellular levels of guanine nucleotides may influence the exchange reaction. To test this hypothesis we measured the levels of nucleotides in yeast cells under different growth conditions and the relative amount of Ras2-GTP. The intracellular GTP/GDP ratio was found to be very sensitive to growth conditions: the ratio is high, close to that of ATP/ADP during exponential growth, but it decreases rapidly before the beginning of stationary phase, and it drops further under starvation conditions. The addition of glucose to glucose-starved cells causes a fast increase of the GTP/GDP ratio. The relative amount of Ras2-GTP changes in a parallel way suggesting that there is a correlation with the cytosolic GTP/GDP ratio. In addition 'in vitro' mixed-nucleotide exchange experiments done on purified Ras2 protein demonstrated that the GTP and GDP concentrations influence the extent of Ras2-GTP loading giving further support to their possible regulatory role. © 2001 Elsevier Science B.V.
Articolo in rivista - Articolo scientifico
Nutrient, Growth regulation, Guanine nucleotide exchange factor, CDC25, Ras, Saccharomyces cerevisiae
English
2001
1538
2-3
181
189
none
Rudoni, S., Colombo, S., Coccetti, P., Martegani, E. (2001). Role of guanine nucleotides in the regulation of the Ras/cAMP pathway in Saccharomyces cerevisiae. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH, 1538(2-3), 181-189 [10.1016/S0167-4889(01)00067-2].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/12437
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