Ramamoorthy S, Balasubramanian A S
Department of Neurological Sciences, Christian Medical College Hospital, Vellore, India.
Arch Biochem Biophys. 1991 May 1;286(2):433-40. doi: 10.1016/0003-9861(91)90062-n.
A 68-kDa protein that was tyrosine phosphorylated in the presence of Zn2+ and two proteins of 52 and 46 kDa that were tyrosine phosphorylated in the presence of Mg2+ were separated by column chromatography of a sheep platelet high speed supernatant on poly(Glu, Tyr)4:1 copolymer-Sepharose or tyrosine-Sepharose. Phosphorylation of the 68-kDa protein occurred maximally in the presence of Zn2+ while Mg2+ was ineffective. The kinases responsible for the Zn(2+)- and Mg(2+)-dependent tyrosine phosphorylation could also tyrosine phosphorylate poly(Glu, Tyr)4:1, histone, and angiotensin II with the same metal ion specificity. The two tyrosine kinase activities could be also distinguished by their differential response to polyamines and quercetin. Zn2+ stimulation did not appear to be due to the inhibition of a protein tyrosine phosphatase. Sephadex G-100 gel filtration of the fraction showing Zn(2+)-dependent tyrosine phosphorylation of the 68-kDa protein showed that the tyrosine kinase activity corresponded to a molecular mass of 68,000 and it showed a protein band of 68 kDa as detected by silver staining on sodium dodecyl sulfate-polyacrylamide gel.
通过用聚（谷氨酸，酪氨酸）4:1共聚物-琼脂糖或酪氨酸-琼脂糖对绵羊血小板高速上清液进行柱色谱分离，得到了一种在Zn2+存在下发生酪氨酸磷酸化的68-kDa蛋白以及两种在Mg2+存在下发生酪氨酸磷酸化的52-kDa和46-kDa蛋白。68-kDa蛋白的磷酸化在Zn2+存在时达到最大值，而Mg2+则无作用。负责Zn(2+)和Mg(2+)依赖性酪氨酸磷酸化的激酶也能以相同的金属离子特异性使聚（谷氨酸，酪氨酸）4:1、组蛋白和血管紧张素II发生酪氨酸磷酸化。这两种酪氨酸激酶活性还可通过它们对多胺和槲皮素的不同反应来区分。Zn2+的刺激似乎不是由于抑制了蛋白酪氨酸磷酸酶。对显示68-kDa蛋白的Zn(2+)依赖性酪氨酸磷酸化的部分进行Sephadex G-100凝胶过滤，结果表明酪氨酸激酶活性对应的分子量为68,000，并且在十二烷基硫酸钠-聚丙烯酰胺凝胶上经银染检测显示有一条68-kDa的蛋白带。
