ACTIVATION OF PRK1 BY PHOSPHATIDYLINOSITOL 4,5-BISPHOSPHATE AND PHOSPHATIDYLINOSITOL 3,4,5-TRISPHOSPHATE - A COMPARISON WITH PROTEIN-KINASE-C ISOTYPES
ACTIVATION OF PRK1 BY PHOSPHATIDYLINOSITOL 4,5-BISPHOSPHATE AND PHOSPHATIDYLINOSITOL 3,4,5-TRISPHOSPHATE - A COMPARISON WITH PROTEIN-KINASE-C ISOTYPES
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DOI：
10.1074/jbc.270.38.22412
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发表时间：
1995-09-22
影响因子：
4.8
通讯作者：
PARKER, PJ
中科院分区：
文献类型：
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作者：
PALMER, RH;DEKKER, LV;PARKER, PJ
作为多聚磷脂酰肌醇的潜在靶点，蛋白激酶C(PKC)亚型(β(1)、epsilon、Zeta、Eta)和PKC相关激酶(PRK)家族成员PRK1的活性在体外进行了比较。PRK1可以被磷脂酰肌醇4，5-二磷酸(PtdIns 4，5-P-2)和磷脂酰肌醇3，4，5-三磷酸(PtdIns-3，4，5-P-3)激活，无论是作为纯脂还是在洗涤剂混合胶束中。在超声作用下，PtdIns-4，5-P-2和PtdIns-3，4，5-P-3激活PRK1的作用相同，而超声作用的磷脂酰肌醇(PtdIns)和磷脂酰丝氨酸(PtdSer)也同样有效。在洗涤剂混合胶束中，PtdIns-4、B-P-2和PtdIns-3、4，5-P-3也显示出类似的效价，但PtdIns和PtdSer的效价比PtdIns和PtdSer低10倍。同样，在洗涤剂混合胶束中，PtdIns-4，5-P-2和PtdIns-3，4，5-P-3都能激活PKC-β(1)、-epsilon和-eta。所有测试的PtdIns-4，5-P和PtdIns-3，4，5-P的激活常数基本相同，这意味着在体外分析中没有特异性。与这一结论一致的是，PtdIns-4，5-P-2和PtdIns-3，4，5-P-3的作用在10 mM的镁离子下被抑制，并被高浓度的六磷酸肌醇和六硫酸肌醇模拟。根据它们作为第二信使的潜在作用，讨论了这两类脂激活蛋白激酶对这些磷脂酰肌醇的相似反应。
As potential targets for polyphosphoinositides, activation of protein kinase C (PKC) isotypes (beta(1), epsilon, zeta, eta) and a member of the PKC-related kinase (PRK) family, PRK1, has been compared in vitro. PRK1 is shown to be activated by both phosphatidylinositol 4,5-bisphosphate (PtdIns 4,5-P-2) as well as phosphatidylinositol 3,4,5-trisphosphate (PtdIns-3,4,5-P-3) either as pure sonicated lipids or in detergent mixed micelles. When presented as sonicated lipids, PtdIns-4,5-P-2 and PtdIns-3,4,5-P-3 were equipotent in activating PRK1, and, furthermore, sonicated phosphatidylinositol (PtdIns) and phosphatidylserine (PtdSer) were equally effective. In detergent mixed micelles, PtdIns-4,B-P-2 and PtdIns-3,4,5-P-3 also showed a similar potency, but PtdIns and PtdSer were 10-fold less effective in this assay. Similarly, PKC-beta(1), -epsilon, and -eta were all activated by PtdIns-4,5-P-2 and PtdIns-3,4,5-P-3 in detergent mixed micelles. The activation constants for PtdIns-4,5-P, and PtdIns-3,4,5-P, were essentially the same for all the kinases tested, implying no specificity in this in vitro analysis. Consistent with this conclusion, the effects of PtdIns-4,5-P-2 and PtdIns-3,4,5-P-3 were found to be inhibited at 10 mM Mg2+ and mimicked by high concentrations of inositol hexaphosphate and inositol hexasulfate. The similar responses of these two classes of lipid-activated protein kinase to these phosphoinositides are discussed in light of their potential roles as second messengers.