TY - JOUR
T1 - Sensitivity of wild type and mutant ras alleles to Ras specific exchange factors
T2 - Identification of factor specific requirements
AU - Nielsen, Klaus Hvid
AU - Gredsted, Lars
AU - Broach, James R.
AU - Willumsen, Berthe Marie
N1 - Funding Information:
We thank Marianne Knudsen and Rikke Ingvorsen for technical assistance and Jeffrey DeClue for constructing the KB gene. The introduction to S. cerevisiae manipulations by Steen Holmberg is gratefully acknowledged, and we thank James Stone, Adrienne Cox, Alan Hall, Channing Der, and Douglas Lowy for providing materials; Douglas Lowy and Malene Hansen for reading the manuscript, and Kaare Teilum for help with Figure 6. This work was supported by NIH Grant CA41086 to JRB, and grants 97 100 13 from the Danish Cancer Society and 9600821 from the Danish Medical Research council to BM Willumsen.
PY - 2001/4/19
Y1 - 2001/4/19
N2 - We have investigated the productive interaction between the four mammalian Ras proteins (H-, N-, KA- and KB-Ras) and their activators, the mammalian exchange factors mSos1, GRF1 and GRP, by using a modified Saccharomyces cerevisiae whose growth is dependent on activation of a mammalian Ras protein by its activator. All four mammalian Ras proteins were activated with similar efficiencies by the individual exchange factors. The H-Ras mutant V103E, which is competent for membrane localization, nucleotide binding, intrinsic and stimulated GTPase activity as well as intrinsic exchange, was defective for activation by all factors tested, suggesting that the integrity of this residue is necessary for catalyzed exchange. However, when other H-Ras mutants were studied, some distinct sensitivities to the exchange factors were observed. GRP-mediated, but not mSos1-mediated, exchange was blocked in additional mutants, suggesting different structural requirements for GRP. Analysis of Ras-mediated gene activation in murine fibroblasts confirmed these results.
AB - We have investigated the productive interaction between the four mammalian Ras proteins (H-, N-, KA- and KB-Ras) and their activators, the mammalian exchange factors mSos1, GRF1 and GRP, by using a modified Saccharomyces cerevisiae whose growth is dependent on activation of a mammalian Ras protein by its activator. All four mammalian Ras proteins were activated with similar efficiencies by the individual exchange factors. The H-Ras mutant V103E, which is competent for membrane localization, nucleotide binding, intrinsic and stimulated GTPase activity as well as intrinsic exchange, was defective for activation by all factors tested, suggesting that the integrity of this residue is necessary for catalyzed exchange. However, when other H-Ras mutants were studied, some distinct sensitivities to the exchange factors were observed. GRP-mediated, but not mSos1-mediated, exchange was blocked in additional mutants, suggesting different structural requirements for GRP. Analysis of Ras-mediated gene activation in murine fibroblasts confirmed these results.
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U2 - 10.1038/sj.onc.1204306
DO - 10.1038/sj.onc.1204306
M3 - Article
C2 - 11360193
AN - SCOPUS:0035912081
SN - 0950-9232
VL - 20
SP - 2091
EP - 2100
JO - Oncogene
JF - Oncogene
IS - 17
ER -