Characterization of rat kidney proximal tubule brush border membrane-associated phosphatidylinositol phosphodiesterase.
Characterization of rat kidney proximal tubule brush border membrane-associated phosphatidylinositol phosphodiesterase.
复制标题
大鼠肾近端小管刷状缘膜相关磷脂酰肌醇磷酸二酯酶的表征。
DOI：
10.1016/0003-9861(83)90243-6
复制
发表时间：
1983
影响因子：
3.9
通讯作者：
Venkatachalam,MA
中科院分区：
文献类型：
--
作者：
Schwertz,DW;Kreisberg,JI;Venkatachalam,MA
当与[3H]花生四烯酸标记的脂质、Ca2+和脱氧胆酸盐一起孵育时，离体的大鼠肾近端小管刷状缘膜囊泡表现出二酰甘油水平增加（20至30倍），并且磷脂酰肌醇随之减少。游离花生四烯酸、甘油三酯和非肌醇磷脂的水平没有改变。这些结果表明磷脂酰肌醇磷酸二酯酶活性与大鼠近曲小管刷状缘膜相关。脱氧胆酸盐和某些二价阳离子的存在对于证明酶活性是必要的。最适pH范围为7.0至8.5。 Ca2+、Mg2+ 和 Mn2+ 刺激甘油二酯的产生，而 Ba2+、Zn2+、Hg2+ 和 K+ 则无效。 HgCl2 抑制 Ca2+ 刺激的磷脂酰肌醇磷酸二酯酶。 Mg2+ 和脱氧胆酸依赖性酶活性被证明具有磷脂酰肌醇特异性。在 Ca2+ 存在下，十二烷基硫酸钠、十四烷基三甲基溴化铵和 Triton X-100 不会激活磷脂酰肌醇磷酸二酯酶。与脱氧胆酸盐结合使用时，甘油二酯的形成不受十二烷基硫酸钠的影响，被 Triton X-100 部分抑制，并被十四烷基三甲基溴化铵完全消除。未发现甘油二酯激酶活性与刷状缘膜磷脂酰肌醇磷酸二酯酶相关。 ATP (1–5 mm) 通过螯合所需的二价阳离子来抑制 Ca2+- 或 Mg2+- 刺激的脱氧胆酸依赖性磷脂酰肌醇水解。
Isolated rat kidney proximal tubule brush border membrane vesicles exhibit an increase in diacylglycerol levels (20- to 30-fold) and a concomitant decrease in phosphatidylinositol when incubated with [3H]arachidonate-labeled lipids, Ca2+, and deoxycholate. Levels of free arachidonate, triglyceride, and noninositol phospholipids are not altered. These results suggest phosphatidylinositol phosphodiesterase activity is associated with rat proximal tubule brush border membrane. Presence of both deoxycholate and certain divalent cations was necessary to demonstrate enzyme activity. Optimum pH ranged from 7.0 to 8.5. Ca2+, Mg2+, and Mn2+stimulated diglyceride production while Ba2+, Zn2+, Hg2+, and K+were ineffective. HgCl2inhibited Ca2+-stimulated phosphatidylinositol phosphodiesterase. Mg2+and deoxycholate-dependent enzyme activity was shown to be phosphatidylinositol specific. Sodium lauryl sulfate, tetradecyltrimethylammonium bromide, and Triton X-100 did not activate phosphatidylinositol phosphodiesterase in the presence of Ca2+. In combination with deoxycholate, diglyceride formation was not affected by sodium lauryl sulfate, partially inhibited by Triton X-100, and completely abolished by tetradecyltrimethylammonium bromide. Diglyceride kinase activity was not found associated with brush border membrane phosphatidylinositol phosphodiesterase. ATP (1–5 mm) inhibited Ca2+- or Mg2+-stimulated, deoxycholate-dependent phosphatidylinositol hydrolysis by chelating the required divalent cation.