胰岛素受体酪氨酸蛋白激酶对醛糖还原酶的磷酸化作用

从人胎盘纯化了醛糖还原酶和部分纯化了胰岛素受体。通过磷酸化实验证明：醛糖还原酶是胰岛素受体酪氨酸蛋白激酶的底物，经分析揭示：胰岛素受体酪氨酸蛋白激酶可将醛糖还原酶的第４０位和第４９位的酪氨酸残基磷酸化。在试管内，未磷酸化的醛糖还原酶和磷酸化的醛糖还原酶的动力学常数无差异，而细胞内的情况有待于进一步研究，本实验提示：醛糖还原酶除具酶活性外，可能还有在细胞内传递胰腺素信息的功能。

Insulin-Receptor Tyrosine Kinase Phosphorylated Aldose Reductase

Insulin receptor from human placenta is partially purified by wheat germ lectin-Sepharose 4B. Aldose reductaseof human placenta is purified by DE-52 cellulose column chromatography, PBE-94 chromatofocus, NADP+-Sepharose 4B affinity chromatography and Sephadex G-100 gel filtration. The phosphorylation assay proves that aldose reductase is the substrate of insulin-receptor tyrosine kinase and the Tyr(40) and Tyr(49) are phosphorylated by the kinase. There is no difference between the kinetic constants of aldose reductase and phosphorylated aldose reductase in vitro. The experiment suggests that in cells AR could trasnmit insulin message besides having enzyme activity.