A novel membrane factor stimulates guanine nucleotide exchange reaction of ras proteins.
A factor with a molecular weight of 100 kDa, which markedly enhanced the guanine nucleotide exchange reaction of ras p21 proteins, was partially purified from bovine brain tissues. The factor was predominantly associated with the plasma membrane. When the partially purified factor and excess cold GTP were added to [3H]GDP.Gly12 p21 or Val12 in the presence of 2 mM MgCl2, the nucleotide exchange rate was stimulated up to 25-fold. The stimulation of the p21-nucleotide exchange reaction by the factor was completely blocked by the Y13-259 ras-neutralizing antibody. Taken together, these results suggest that the factor may control the rate limiting GDP/GTP exchange step in recycling of p21 in ras-mediated signal transduction.
Biological Carcinogenesis and Development Program, Program Resources, Inc. Frederick, MD.
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M
West
H F
HF
Kung
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T
Kamata
D000818:Animals; D001921:Brain / Q000378:metabolism*; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D020690:GTPase-Activating Proteins; D011905:Genes, ras; D006150:Guanine Nucleotides / Q000378:metabolism*; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D007700:Kinetics; D008565:Membrane Proteins / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011506:Proteins / Q000302:isolation & purification / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D016283:Proto-Oncogene Proteins p21(ras); D020703:ras GTPase-Activating Proteins
D020690:GTPase-Activating Proteins; D006150:Guanine Nucleotides; D008565:Membrane Proteins; D011506:Proteins; D011518:Proto-Oncogene Proteins; D020703:ras GTPase-Activating Proteins; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; D011505:Protein-Tyrosine Kinases; D016283:Proto-Oncogene Proteins p21(ras)