Publikationsdatum:
1990-04-06
Beschreibung:
The rate of release of guanine nucleotides from the ras proteins (Ras) is extremely slow in the presence of Mg2+. It seemed likely, therefore that a factor might exist to accelerate the release of guanosine diphosphate (GDP), and hence the exchange of GDP for guanosine triphosphate (GTP). Such a factor has now been discovered in rat brain cytosol. Brain cytosol was found to catalyze, by orders of magnitude, the release of guanine nucleotides from recombinant v-H-Ras protein bound with [alpha-32P]GDP. This effect occurred even in the presence of a large excess of Mg2+, but was destroyed by heat or by incubation of the cytosol for an hour at 37 degrees C in the absence of phosphatase inhibitors. The effect was observed with either v-H-Ras or c-H-Ras, but not with p25rab3A, a small G protein with about 30% similarity to Ras. The effect could not be mimicked by addition of recombinant Ras-GAP or purified GEF, a guanine nucleotide exchange factor involved in the regulation of eukaryotic protein synthesis. By gel filtration chromatography, the factor appears to possess a molecular size between 100,000 and 160,000 daltons. This protein (Ras-guanine nucleotide-releasing factor, or Ras-GRF) may be involved in the activation of p21ras.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wolfman, A -- Macara, I G -- CA 43551/CA/NCI NIH HHS/ -- ES 01247/ES/NIEHS NIH HHS/ -- GM 41220/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Apr 6;248(4951):67-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biophysics, University of Rochester Medical Center, NY 14642.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2181667" target="_blank"〉PubMed〈/a〉
Schlagwort(e):
Animals
;
Binding, Competitive
;
Brain/metabolism
;
Cholic Acids
;
Cytosol/*metabolism
;
Guanine Nucleotides/*metabolism
;
Guanosine 5'-O-(3-Thiotriphosphate)
;
Guanosine Diphosphate/*metabolism
;
Guanosine Triphosphate/analogs & derivatives/metabolism
;
Hot Temperature
;
Immunosorbent Techniques
;
Kinetics
;
Magnesium Chloride/pharmacology
;
Molecular Weight
;
Proto-Oncogene Proteins/*metabolism
;
Proto-Oncogene Proteins p21(ras)
;
Rats
;
Thionucleotides/metabolism
Print ISSN:
0036-8075
Digitale ISSN:
1095-9203
Thema:
Biologie
,
Chemie und Pharmazie
,
Informatik
,
Medizin
,
Allgemeine Naturwissenschaft
,
Physik
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