摘要
以生长3－4d的玉米（ZeamaysL．）根尖为材料，用两相法得到高纯度的质膜，鉴定了质膜上存在一受钙激活的蛋白激酶。该类激酶主要位于质膜内侧；钙的半激活浓度为50μmol／L；外源钙调素对激酶没有明显的活化作用；钙调素拮抗剂三氟拉嗪（TFP）可明显抑制激酶活性，半抑制浓度为75μmol／L；该类激酶对外源底物组蛋白ⅢS型有较高的特异性。结果显示此激酶属于钙依赖钙调素不依赖蛋白激酶。质膜上33kD和58kD两种蛋白可能是这种钙依赖蛋白激酶的内源底物。
Plasma membrane (PM) of high purity was prepared through a two-phase aqueous system from rootsof 3-4 d old corn (Zea mays L. ) seedling, and within which calcium-activated protein kinase was identified. The kinase was mainly located in the inner side of the PM with a semi-activation concentration to freecalcium ion of 50 μmol/L. Exogenous CaM had no agonistic effect on the protein kinase but CaM antagonistTFP could strongly inhibit its activity with a semi-inhibition concentration of 75 μmol/L. The protein kinaseshowed high specificity for the exogenous substrate, Histone ⅢS. These results indicated that this protein kinase could be a calcium-dependent and calmodulin-independent protein kinase (CDPK). Moreover, two pro teins (33 kD and 58 kD) in PM might be the endogenous substrates of the CDPK.
基金
国家自然科学基金
国家教委博士点专项科研基金
关键词
玉米
根
质膜
钙
钙依赖蛋白激酶
Corn met, Plasma membrane, Calcium, Calcium-dependent protein kinase
