REGULATION OF PROTEIN-TYROSINE KINASES IN PLATELETS

Platelet activation is accompanied by a dramatic increase in tyrosine phosphorylation of many cellular proteins. Phosphorylation of these pr oteins occurs in successive waves during the activation process, sugge sting that several distinct mechanisms, occurring in a temporal order, regulate protein tyrosine kinases and/or phosphatases in activated pl atelets. Several tyrosine kinases, including Src family kinases, Syk a nd FAK, have been implicated in these phosphorylation events. These ki nases are regulated by distinct receptor-mediated events involving act ivation of their catalytic activity and alterations in their cellular localization.