title: Common elements in growth factor stimulation and oncogenic transformation: 85 kd phosphoprotein and phosphatidylinositol kinase activity.
abstract: The phosphorylation of proteins on tyrosine in vivo and in vitro was examined in 3T3 cells stimulated by platelet-derived growth factor (PDGF) and transformed by polyoma middle T antigen (MTAg) by using an antibody directed against phosphotyrosine (P-tyr). Two common events were observed upon PDGF stimulation or MTAg transformation of cells: the appearance in the immunoprecipitates of an 85 kd phosphoprotein, and increased phosphatidylinositol (PI) kinase activity. In PDGF-stimulated cells, the 85 kd phosphoprotein and PI kinase activity appeared rapidly, within 1 min of growth factor addition. The PI kinase activity and 85 kd phosphorylation were also increased in anti-P-tyr immunoprecipitates from cells transformed by v-fms and v-sis, but not by SV40 T antigen. The presence of the tyrosine-phosphorylated 85 kd protein correlated with PI kinase activity during several purification steps. These results suggest that the 85 kd phosphoprotein, a putative PI kinase, is a substrate for both the PDGF receptor and MTAg/pp60c-src tyrosine kinase activities.
mesh_terms: D019870:1-Phosphatidylinositol 4-Kinase; D000818:Animals; D000952:Antigens, Polyomavirus Transforming; D000957:Antigens, Viral, Tumor / Q000494:pharmacology*; D002460:Cell Line; D002471:Cell Transformation, Neoplastic / Q000378:metabolism*; D002472:Cell Transformation, Viral; D005786:Gene Expression Regulation / Q000187:drug effects; D051379:Mice; D008807:Mice, Inbred BALB C; D016281:Oncogene Protein gp140(v-fms); D020575:Oncogene Proteins v-sis; D009856:Oncogene Proteins, Viral / Q000494:pharmacology*; D009857:Oncogenes; D010716:Phosphatidylinositols / Q000378:metabolism; D010750:Phosphoproteins / Q000302:isolation & purification* / Q000378:metabolism; D010766:Phosphorylation; D010770:Phosphotransferases / Q000302:isolation & purification* / Q000378:metabolism; D019000:Phosphotyrosine; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D011120:Polyomavirus / Q000201:enzymology; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D012191:Retroviridae Proteins / Q000502:physiology; D013539:Simian virus 40 / Q000502:physiology; D013379:Substrate Specificity; D014443:Tyrosine / Q000031:analogs & derivatives / Q000032:analysis
chemical_list: D000952:Antigens, Polyomavirus Transforming; D000957:Antigens, Viral, Tumor; D016281:Oncogene Protein gp140(v-fms); D020575:Oncogene Proteins v-sis; D009856:Oncogene Proteins, Viral; D010716:Phosphatidylinositols; D010750:Phosphoproteins; D010982:Platelet-Derived Growth Factor; D012191:Retroviridae Proteins; D019000:Phosphotyrosine; D014443:Tyrosine; D010770:Phosphotransferases; D019870:1-Phosphatidylinositol 4-Kinase; D011505:Protein-Tyrosine Kinases