Endothelin-1 effect on tyrosine phosphorylation and on tyrosine phosphatase (PTP-1C) translocation in rabbit platelets

This study examined the temporal relationships of endothelin-1-stimulated r abbit platelets tyrosine phosphorylated proteins. The effect of endothelin- 1 on tyrosine phosphorylation was dose- and time-dependent and caused rapid tyrosine phosphorylation of three groups of proteins in the molecular mass range 70-100 kDa, 100-150 kDa and 150-200 kDa. Significant protein tyrosin e phosphatase activity and amount were found to be associated with the cyto skeleton of endothelin-1-stimulated rabbit platelets. Under our experimenta l conditions, translocation from the cytosolic fraction to the cytoskeleton reached its highest levels within 10-20 sec of endothelin-1 stimulation. E ndothelin-1-induced translocation of protein tyrosine phosphatase, associat ed with the increase in its activity was demonstrated by immunoblotting and immunoelectron microscopy.