SEPARATION AND IDENTIFICATION OF 2 PHOSPHATIDYLINOSITOL 4-KINASE ACTIVITIES IN BOVINE UTERUS
SEPARATION AND IDENTIFICATION OF 2 PHOSPHATIDYLINOSITOL 4-KINASE ACTIVITIES IN BOVINE UTERUS
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DOI：
10.1016/0006-291x(89)91641-0
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发表时间：
1989-04-14
影响因子：
3.1
通讯作者：
DEUEL, TF
中科院分区：
文献类型：
--
作者：
LI, YS;PORTER, FD;DEUEL, TF
生长因子激活的第二信使途径部分通过磷酸肌醇的分解产物介导。我们从牛子宫中分离出两种磷脂酰肌醇 (PtdIns) 4-激酶，它们似乎是独立调节的。主要的 II 型酶先前已纯化至明显均质； I型酶已被纯化.apprx。 1000 倍（比活性，约 30 nmoles/mg/min）。 I 型和 II 型酶在 ATP 的表观 Km 和对二价阳离子的响应方面存在显着差异。与 II 型酶相比，I 型 PtdIns 激酶对腺苷的抑制具有抵抗力，可通过增加 Triton X-100 浓度来抑制，并且在 pH 值低于 6.5 和高于 8.5 时，其储存稳定性低于 II 型酶。 I 型 PtdIns 4-激酶的表观分子质量为 .apprx。 200 kD 和 .apprx 的 II 型酶。 80 kD。使用酶和化学标准，两种酶都特异性磷酸化 PtdIns 的第四个羟基。因此，结果证实存在两种不同且独立的酶催化 PtdIns 4-激酶活性，具有不同的物理、动力学和调节特性，表明这是调节第二信使信号、转导细胞对生长因子的反应性的重要位点。
Growth factor-activated second messenger pathways are mediated in part via breakdown products of phosphoinositides. We have separated two phosphatidylinositol (PtdIns) 4-Kinases from bovine uteri which appear to be regulated independently. The predominant type II enzyme previously was purfied to apparent homogeneity; the type I enzyme has been purified .apprx. 1000 fold (specific activity, .apprx. 30 nmoles/mg/min). The type I and type II enzymes differ sharply in apparent Km for ATP and response to divalent cations. In contrast to type II enzyme, type I PtdIns kinase was resistant to inhibition by adenosine, inhibited by increasing concentrations of Triton X-100, and less stable to storage than type II enzyme at pH values below 6.5 and above 8.5. Type I PtdIns 4-kinase has an apparent molecular mass of .apprx. 200 kD and type II enzyme of .apprx. 80 kD. Using both enzymatic and chemical criteria, both enzymes specifically phosphorylated the fourth hydroxyl group of PtdIns. The results thus establish the presence of two distinct and separate enzymes catalyzing PtdIns 4-kinase activity with different physical, kinetic, and regulatory properties, suggesting an important site for the regulation of second messenger signals, transducing the responsiveness of cells to growth factors.