Association between the PDGF receptor and members of the src family of tyrosine kinases

We have examined the interaction between the plate-let-derived growth factor (PDGF) receptor and three src family tyrosine kinases, pp60 c- src , p59 fyn , and pp62 c-yes . The kinase activities of all three enzymes were elevated after PDGF stimulation of quiescent fibroblasts, coincident with association of the src family kinases with the PDGF receptor and other proteins. The presence of a protein of 81–85 kd in these complexes correlated with the detection of phosphatidylinositol (PI) kinase activity (previously described to associate with both the PDGF receptor and pp60 c- src -middle T antigen). These results suggest that the physiological response to PDGF involves interaction of the receptor not only with serine/threonine and lipid kinases and a phospholipase, but also with other tyrosine kinases.