Analysis of phosphotyrosine-containing proteins present in v-src-infected myeloid progenitor cells

We examined the phosphotyrosine-containing proteins in v-src-infected myeloid cells. Proteins with relative molecular weights (M(r)) of 180,000, 175,000, 135,000, 125,000, 120,000, 90,000, 75,000, and 60,000 were present in v-src-infected but not in uninfected 32D cl3 cells. Stimulation of 32D cl3 cells with interleukin 3 (IL-3) resulted in the tyrosine phosphorylation of a protein of 150,000 (M(r)), which was not phosphorylated in v-src-infected 32D cl3 cells. A panel of monoclonal antibodies directed against phosphotyrosine-containing proteins in v-src-transformed chicken embryo fibroblasts (3C4, 2A7, 2B12 and 4F11, directed against p210, p125, p120 and p85 respectively) was used to characterize these substrates. We did not observe tyrosine phosphorylation of proteins recognized by these four monoclonal antibodies in either IL-3-stimulated or v-src-infected 32D cl3 cells. However, we did detect tyrosine phosphorylation of proteins recognized by these monoclonal antibodies in v-src-transformed NIH3T3 cells. Tyrosine phosphorylation of GTPase-activating protein (GAP) and the GAP-associated proteins p62 and p190 was observed in v-src-infected 32D cl3 cells. Stimulation of 32D cl3 cells with IL-3 does not induce phosphorylation of GAP or the GAP-associated proteins p62 or p190. These results suggest that substrates for v-src vary between different cell types.