Phosphorylation of JAK2 in thrombin-stimulated human platelets.


We show the presence of the tyrosine kinase JAK2 in human platelets and demonstrate that it undergoes phosphorylation on tyrosine residues on challenge with the G protein receptor stimulus, thrombin, or the tyrosine phosphatase inhibitor, peroxovanadate. Thrombin-induced phosphorylation of JAK2 is inhibited by two structurally distinct inhibitors of tyrosine kinases, staurosporine and the tyrphostin ST271. The protein kinase C (PKC) inhibitor, Ro 31-8220, and intracellular Ca2+ chelator, BAPTA-AM, also inhibit thrombin-induced phosphorylation of JAK2, while the phorbol ester, phorbol dibutyrate (PDBu), and Ca2+ ionophore, A23187, induce tyrosine phosphorylation of JAK2. These results suggest that tyrosine phosphorylation of JAK2 stimulated by thrombin may be mediated downstream of phosphoinositide metabolism.


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@article{RodrguezLiares1994PhosphorylationOJ, title={Phosphorylation of JAK2 in thrombin-stimulated human platelets.}, author={B Rodr{\'i}guez-Li{\~n}ares and Stephen P. Watson}, journal={FEBS letters}, year={1994}, volume={352 3}, pages={335-8} }