title: Regeneration of the GTP-bound from the GDP-bound form of human and yeast ras proteins by nucleotide exchange. Stimulatory effect of organic and inorganic polyphosphates.
abstract: The regeneration of the GTP-bound from the GDP-bound form of purified human and yeast ras proteins occurs in vitro by a nucleotide-exchange reaction. For both human and yeast ras proteins the dissociation of the protein-bound GDP is the rate-limiting step in the presence of Mg ions. The rate of formation of the ras X GTP complex is stimulated by weak Mg2+-chelating agents like ATP and inorganic polyphosphates and, to a lesser extent, by ADP. This suggests a possible mechanism of regulation of ras-dependent pathway(s) by intracellular metabolic products.
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D005656:Fungal Proteins / Q000378:metabolism*; D006150:Guanine Nucleotides / Q000378:metabolism*; D006153:Guanosine Diphosphate / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D011122:Polyphosphates / Q000494:pharmacology*; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D016283:Proto-Oncogene Proteins p21(ras); D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D018631:ras Proteins
chemical_list: D005656:Fungal Proteins; D006150:Guanine Nucleotides; D011122:Polyphosphates; D011518:Proto-Oncogene Proteins; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins