Meyers R, Cantley L C
Department of Cell Biology, Harvard Medical School and Division of Signal Transduction, Beth Israel Hospital, Boston, Massachusetts 02215, USA.
J Biol Chem. 1997 Feb 14;272(7):4384-90. doi: 10.1074/jbc.272.7.4384.
Phosphatidylinositol (PtdIns) 4-kinases catalyze the synthesis of PtdIns-4-P, the immediate precursor of PtdIns-4,5-P2. Here we report the cloning of a novel, ubiquitously expressed PtdIns 4-kinase (PI4Kbeta). The 2.4-kilobase pair cDNA encodes a putative translation product of 801 amino acids which shows greatest homology to the yeast PIK1 gene. The recombinant protein exhibits lipid kinase activity when expressed in Escherichia coli, and specific antibodies recognize a 110-kDa PtdIns 4-kinase in cell lysates. The biochemical properties of PI4Kbeta are characteristic of a type III enzyme. Interestingly, both recombinant PI4Kbeta and the endogenous protein are inhibited by 150 nM wortmannin, suggesting that we have cloned the previously described PtdIns 4-kinase that is responsible for regulating the synthesis of agonist-sensitive pools of polyphosphoinositides (Nakanishi, S., Catt, J. K., and Balla, T. (1995) Proc. Natl. Acad. Sci. U. S. A. 92, 5317-5321).
磷脂酰肌醇（PtdIns）4-激酶催化PtdIns-4-P的合成，PtdIns-4-P是PtdIns-4,5-P2的直接前体。在此我们报告一种新的、在全身广泛表达的PtdIns 4-激酶（PI4Kβ）的克隆。2.4千碱基对的cDNA编码一个推定的含801个氨基酸的翻译产物，该产物与酵母PIK1基因具有最高的同源性。重组蛋白在大肠杆菌中表达时表现出脂质激酶活性，并且特异性抗体能识别细胞裂解物中的一种110 kDa的PtdIns 4-激酶。PI4Kβ的生化特性是III型酶的特征。有趣的是，重组PI4Kβ和内源性蛋白均受到150 nM渥曼青霉素的抑制，这表明我们克隆到了先前描述的负责调节多磷酸肌醇激动剂敏感池合成的PtdIns 4-激酶（中岛，S.，卡特，J. K.，和巴拉，T.（1995年）美国国家科学院院刊92，5317 - 5321）。
