Sada K, Yanagi S, Yamamura H
Department of Biochemistry, Fukui Medical School, Japan.
Biochem Biophys Res Commun. 1994 Apr 15;200(1):1-7. doi: 10.1006/bbrc.1994.1406.
Thrombin dramatically activated p72syk in a time- and dose- dependent fashion in extracts of resting porcine platelets in the presence of EDTA. Separation analysis using Sephacryl S-300 column chromatography has demonstrated that p72syk may exist as large (complex) and small (monomer) forms in resting platelets, and activation of p72syk was only observed in the fraction of large form. Pretreatment with ATP scavenger, GDP beta S and protein phosphatase inhibitors had no effect on this activation. Furthermore, washed immuno-precipitates of large form p72syk were also activated by thrombin or fibrinogen. These results suggest that p72syk may associate with thrombin receptor or other agonist receptors and there may be a novel activation mechanism of non-receptor type protein-tyrosine kinase, which does not require the modification by other protein kinases, protein phosphatases and GTP binding proteins.
在乙二胺四乙酸（EDTA）存在的情况下，凝血酶能以时间和剂量依赖的方式显著激活静息猪血小板提取物中的p72syk。使用Sephacryl S - 300柱色谱进行的分离分析表明，p72syk在静息血小板中可能以大（复合物）和小（单体）两种形式存在，并且p72syk的激活仅在大形式的组分中观察到。用ATP清除剂、GDPβS和蛋白磷酸酶抑制剂进行预处理对这种激活没有影响。此外，大形式p72syk的洗涤免疫沉淀物也能被凝血酶或纤维蛋白原激活。这些结果表明，p72syk可能与凝血酶受体或其他激动剂受体相关联，并且可能存在一种非受体型蛋白酪氨酸激酶的新型激活机制，该机制不需要其他蛋白激酶、蛋白磷酸酶和GTP结合蛋白的修饰。
