title: Physiological correlation between nucleoside-diphosphate kinase and the enzyme-associated guanine nucleotide binding proteins.
abstract: The physiological correlation between NDP-kinase and the enzyme-associated guanine nucleotide binding proteins (G1 and G2) has been studied in vitro. It was found that incubation of the phosphoenzyme (enzyme-bound high-energy phosphate intermediate) of NDP-kinases with one of the nucleoside 5'-diphosphates (NDPs) in the presence of divalent cations (Mg2+ and Ca2+) results in the formation of nucleoside 5'-triphosphates (NTPs) within 40 sec even at low temperatures (below 4 degrees C) without strict base-specificity; and high-energy phosphates on the phosphoenzyme can transfer preferentially to GDP on the guanine nucleotide binding proteins (G1, G2 and r-p21 protein) in the presence of 0.25 mM Ca2+ or 1 mM Mg2+ even if any other NDPs are present in the reaction mixtures. These observations suggest that NDP-kinase may be responsible for the phosphate-transfer between GDP on the guanine nucleotide binding proteins and its phosphoenzyme.
mesh_terms: D000818:Animals; D002286:Carcinoma, Ehrlich Tumor / Q000201:enzymology; D002413:Cations, Divalent; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D009701:Nucleoside-Diphosphate Kinase / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism*; D010770:Phosphotransferases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D012265:Ribonucleotides / Q000378:metabolism
chemical_list: D002413:Cations, Divalent; D010750:Phosphoproteins; D011518:Proto-Oncogene Proteins; D012265:Ribonucleotides; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; D010770:Phosphotransferases; D009701:Nucleoside-Diphosphate Kinase; D019204:GTP-Binding Proteins