淋巴细胞无细胞体系中磷脂酰肌醇合成的二价阳离子依赖性
The bivalent-cation dependence of phosphatidylinositol synthesis in a cell-free system from lymphocytes.
作者信息
Moore J P, Smith G A, Hesketh T R, Metcalfe J C
出版信息
Biochem J. 1983 Jun 15;212(3):691-7. doi: 10.1042/bj2120691.
The bivalent-cation requirements of two enzymes involved in phosphatidylinositol synthesis were defined for pig lymphocyte membranes using a citric acid buffer. CTP:phosphatidic acid cytidylyltransferase (EC 2.7.7.41) is activated by free Mn2+ concentrations above 20nM and by free Mg2+ concentrations above 10 microM. When activated by Mg2+, the enzyme is weakly inhibited by Ca2+ (Ki greater than 250 microM), but Ca2+ has no effect when Mn2+ is used to stimulate CDP-diacylglycerol synthesis. The synthesis of phosphatidylinositol from phosphatidic acid is also stimulated by Mn2+ and Mg2+ concentrations similar to those above and is inhibited by free Ca2+ concentrations above 500nM, probably by its action on CDP-diacylglycerol:inositol 3-phosphatidyltransferase (EC 2.7.8.11). Taken together, these studies suggest that under physiological conditions phosphatidylinositol synthesis is activated by Mg2+ and it is possible that it is further regulated by the free concentrations of Ca2+ and/or Mn2+.
利用柠檬酸缓冲液确定了猪淋巴细胞膜中参与磷脂酰肌醇合成的两种酶对二价阳离子的需求。CTP：磷脂酸胞苷转移酶（EC 2.7.7.41）在游离Mn2+浓度高于20nM以及游离Mg2+浓度高于10μM时被激活。当由Mg2+激活时，该酶受到Ca2+的微弱抑制（Ki大于250μM），但当使用Mn2+刺激CDP - 二酰基甘油合成时，Ca2+没有影响。由磷脂酸合成磷脂酰肌醇也受到与上述相似的Mn2+和Mg2+浓度的刺激，并受到游离Ca2+浓度高于500nM的抑制，这可能是由于其对CDP - 二酰基甘油：肌醇3 - 磷脂酰转移酶（EC 2.7.8.11）的作用。综上所述，这些研究表明，在生理条件下，磷脂酰肌醇的合成由Mg2+激活，并且有可能进一步受到Ca2+和/或Mn2+游离浓度的调节。
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