Effect of L-alpha-phosphatidylinositol on a vascular smooth muscle Ca2+-dependent protease. Reduction of the Ca2+ requirement for autolysis.
Effect of L-alpha-phosphatidylinositol on a vascular smooth muscle Ca2+-dependent protease. Reduction of the Ca2+ requirement for autolysis.
复制标题
L-α-磷脂酰肌醇对血管平滑肌 Ca2 依赖性蛋白酶的影响。
DOI：
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发表时间：
1984
影响因子：
4.8
通讯作者：
D. Hathaway
中科院分区：
文献类型：
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作者：
S. A. Coolican;D. Hathaway
血管平滑肌含有大量的Ca 2+依赖性蛋白酶。类似于先前从鸡砂囊平滑肌纯化的Ca 2+依赖性蛋白酶（海瑟薇，D. R.，Werth，D. K.，和Haeberle，J. R.（1982）J.Biol.Chem.257，9072-9077），哺乳动物血管肌肉蛋白酶是由76，000-和30，000-道尔顿亚基（IIa）组成的异二聚体。该酶可在Ca 2+存在下发生自溶，产生由76，000-和18，000-道尔顿亚基组成的较小种类（IIb）。自溶大大降低了催化活性的Ca 2+依赖性。自溶物种，IIb，是约23倍更敏感的Ca 2+（K0.5 = 39微M）比天然酶，IIa（K0.5 = 891微M）。在这篇文章中，我们报告磷脂酰肌醇和在较小程度上的一种代谢衍生物，二油酰甘油，刺激自溶的血管Ca 2+依赖性蛋白酶减少的Ca 2+自溶从K0.5 = 680 μ M的情况下的脂质K0.5 = 87 μ M的磷脂酰肌醇和二油酰甘油的存在下。此外，减少的钙离子的要求自溶产生的磷脂酰肌醇被拮抗的磷脂结合药物，三氟拉嗪。此外，磷脂酰肌醇的作用是特定的自溶，没有几个磷脂或衍生物测试改变的Ca 2+依赖性或最大速率的蛋白质降解的自溶产物，IIb。我们的研究结果表明，自溶可能是一个重要的初始步骤，在激活血管平滑肌中的Ca 2+依赖性蛋白酶，这一步可能是由Ca 2+和磷脂酰肌醇的组合调节。
Vascular smooth muscle contains large amounts of a Ca2+-dependent protease. Similar to a Ca2+-dependent protease previously purified from chicken gizzard smooth muscle (Hathaway, D. R., Werth, D. K., and Haeberle, J. R. (1982) J. Biol. Chem. 257, 9072-9077), the mammalian vascular muscle protease is a heterodimer consisting of 76,000- and 30,000-dalton subunits (IIa). The enzyme can undergo autolysis in the presence of Ca2+ to produce a smaller species consisting of 76,000- and 18,000-dalton subunits (IIb). Autolysis greatly reduces the Ca2+ dependence of catalytic activity. The autolytic species, IIb, was approximately 23-fold more sensitive to Ca2+ (K0.5 = 39 microM) than the native enzyme, IIa (K0.5 = 891 microM). In this communication, we report that phosphatidylinositol and to a lesser extent one metabolic derivative, dioleoylglycerol, stimulate autolysis of the vascular Ca2+-dependent protease by reducing the Ca2+ for autolysis from K0.5 = 680 microM in the absence of lipid to K0.5 = 87 microM in the presence of both phosphatidylinositol and dioleoylglycerol. Moreover, the reduction in the Ca2+ requirement for autolysis produced by the phosphatidylinositol was antagonized by the phospholipid-binding drug, trifluoperazine. In addition, the effect of phosphatidylinositol was specific for autolysis, and none of several phospholipids or derivatives tested altered the Ca2+ dependence or maximal rate for protein degradation of the autolytic product, IIb. Our results suggest that autolysis may be an important initial step in the activation of the Ca2+-dependent protease in vascular smooth muscle and that this step may be regulated by a combination of Ca2+ and phosphatidylinositol.