title: GTP-binding proteins and adenylate cyclase activity in v-Ki-ras transformed NIH/3T3 fibroblast cells.
abstract: To identify the role of ras oncogene and p21 in the coupling mechanism of GTP-binding proteins to adenylate cyclase, we used v-Ki-ras transformed NIH/3T3 fibroblast cells. In the previous study, we investigated that NaF, cholera toxin and forskolin remarkably enhanced the adenylate cyclase activity in transformed cells compared to normal NIH/3T3 cells. In the present study, adenylate cyclase was more enhanced by GTP gamma S in transformed cells than in normal cells. It was considered that p21 plays enhancing role in coupling of GTP-binding proteins to adenylate cyclase. Further, as measured by the degree of [32P] ADP-ribosylation of GTP-binding proteins by cholera toxin and pertussis toxin respectively, the amount of Gs (46 kDa) was almost equal in both cells, while the amount of Gi (41 kDa) in transformant was about one third of that in normal cells. This difference seems to be reflected in either the biological situations or the quantities of Gi. Our data suggest that v-Ki-ras transformation resulted in the decrease of Gi protein so that the inhibitory regulation on adenylate cyclase relatively becomes low and then stimulatory influence of Gs seems to be enhanced.
mesh_terms: D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D002471:Cell Transformation, Neoplastic / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D011905:Genes, ras; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D007700:Kinetics; D051379:Mice; D008970:Molecular Weight; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras); D013873:Thionucleotides / Q000494:pharmacology
chemical_list: D011518:Proto-Oncogene Proteins; D013873:Thionucleotides; D000246:Adenosine Diphosphate Ribose; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate; D019204:GTP-Binding Proteins; D016283:Proto-Oncogene Proteins p21(ras); D000262:Adenylyl Cyclases