Ferrell J E, Martin G S
Department of Zoology, University of California, Berkeley 94720.
Mol Cell Biol. 1988 Sep;8(9):3603-10. doi: 10.1128/mcb.8.9.3603-3610.1988.
Intact human platelets, terminally differentiated cells with no growth potential, were found to possess unusually high levels of tyrosine-specific protein phosphorylation. The physiological platelet activator thrombin transiently elevated platelet phosphotyrosine content, apparently through stimulation of one or more tyrosine-specific protein kinases. Immunoblotting with antiphosphotyrosine antiserum showed that thrombin caused dramatic changes in the tyrosine phosphorylation of a number of individual protein bands and that these changes occurred in three distinct temporal waves. Most but not all of the protein bands phosphorylated at tyrosine in response to thrombin were also tyrosine phosphorylated in response to chilling or the combination of ionophore A23187 and tetradecanoylphorbol acetate. Thrombin stimulated the phosphorylation of the tyrosine kinase pp60c-src, primarily at Ser-12 and Tyr-527, although the effects of these phosphorylations on platelet pp60c-src function were not apparent. Together, these results suggest that tyrosine-specific protein kinases of uncertain identity are involved in signal transduction in platelets.
完整的人类血小板是没有生长潜能的终末分化细胞，被发现具有异常高水平的酪氨酸特异性蛋白磷酸化。生理性血小板激活剂凝血酶会短暂提高血小板磷酸酪氨酸含量，显然是通过刺激一种或多种酪氨酸特异性蛋白激酶来实现的。用抗磷酸酪氨酸抗血清进行免疫印迹分析表明，凝血酶会导致多个单独蛋白条带的酪氨酸磷酸化发生显著变化，并且这些变化以三个不同的时间波形式出现。响应凝血酶而在酪氨酸位点磷酸化的大多数（但不是全部）蛋白条带，在受到冷刺激或离子载体A23187与十四酰佛波醇乙酸酯联合作用时，也会发生酪氨酸磷酸化。凝血酶刺激酪氨酸激酶pp60c-src的磷酸化，主要发生在Ser-12和Tyr-527位点，尽管这些磷酸化对血小板pp60c-src功能的影响并不明显。总之，这些结果表明身份不明的酪氨酸特异性蛋白激酶参与了血小板中的信号转导。
