高温胁迫下葡萄叶片蛋白激酶的诱导形成与活性变化

以"京秀"葡萄(Vitis vinifera L.cv.Jingxiu)幼苗为试材,研究了高温胁迫激活的蛋白激酶的类型和活性.结果表明,高温胁迫10～60min明显地激活了一个分子量约为52 kD的蛋白激酶,该蛋白激酶能将凝胶中所嵌入的髓鞘碱性蛋白(MBP)磷酸化,在放射自显影中表现出很高的放射活性,而对凝胶中的组蛋白-Ⅲ(histone-Ⅲ)则没有这样的作用.在溶液反应体系中该蛋白激酶对MBP也表现出很高的磷酸化活性,而对histone-Ⅲ却无作用.Ca2 对其活性变化无显著影响.酪氨酸特异性蛋白磷酸酶(YOP)对该激酶的活性有显著的钝化作用.结果表明该52 kD蛋白激酶是MAPK家族中的一种.

Induction and Activity Changes of Protein Kinase in Grape Leaves Under Heat Stress

The type and activity of protein kinase induced and activated by heat stress were studied in leaves of "Jingxiu" grape (Vitis vinifera L. cv. Jingxiu). The results showed that a 52-kD protein kinase was evidently activated by heat stress in 10 to 60 min. Myelin basic protein (MBP) embedded in gel could be phosphorylated by the 52 kD protein kinase. The phosphorylating activity of this kinase was determined by using MBP as the substrate and measuring the products of phosphorylation by autoradiography. The 52 kD protein kinase could not affect histone-III embedded as the substrate in gel and the products of phosphorylation by autoradiography was not displayed. High phosphorylation activity of this protein kinase was found with MBP substrate in solution reaction system. After 60 min heat stress, the activity of this protein kinase reached its maximum value, and then declined rapidly. Compared with control, the activity of protein kinase had no difference when histone-III was used as substrate in reaction system. The activity of this protein kinase was not enhanced by Ca(2+), showing that it was not Ca(2+)-dependent. The tyrosine-specific protein phosphatase (YOP) could significantly inactivate the phosphorylation activity of protein kinase. All results demonstrate that the 52 kD protein kinase activated by heat stress belong to the MAPK family.