Translocation of an SH2‐containing protein tyrosine phosphatase (SH‐PTP1) to the cytoskeleton of thrombin‐activated platelets

Abstract
A significant protein tyrosine phosphatase (PTP) activity was found to be associated with the cytoskeleton of thrombin‐stimulated platelets. Translocation of the enzyme became maximal within 1‐2 min of thrombin stimulation and was suppressed by cytochalasin D or upon inhibition of aggregation. Immunoblotting as well as immunoprecipitation revealed that a PTP with two SH2 domains (SH‐PTP1) displayed the same behaviour, translocation to the cytoskeleton showing the same time course as that observed for pp60 c‐src . We conclude that SH‐PTP1 might represent a critical enzyme in the complex interplay between the various proteins regulating protein tyrosine phosphorylation in the cytoskeletal matrix.