Phosphorylation of phosphatidylinositol in rat liver Golgi.
Phosphorylation of phosphatidylinositol in rat liver Golgi.
复制标题
大鼠肝脏高尔基体中磷脂酰肌醇的磷酸化。
DOI：
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发表时间：
1983
影响因子：
4.8
通讯作者：
R. Sundler
中科院分区：
文献类型：
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作者：
B. Jergil;R. Sundler
研究了大鼠肝脏亚细胞组分中磷脂酰肌醇的磷酸化。高尔基体中富集的部分显示出最高的比活性，而高尔基体中缺失的质膜部分以及粗粒体、线粒体和无颗粒上清液的活性要低得多。[γ - 32p]ATP与内源性或外源性添加的磷脂酰肌醇形成的产物以二磷酸肌醇为主，三磷酸肌醇含量不超过5%。磷脂酰肌醇激酶的最适pH值为7.8左右，活性最高。除极高浓度外，Triton X-100对激酶反应无明显抑制作用，而洋地黄苷对激酶反应有明显抑制作用。外源性磷脂酰肌醇以超声囊泡的形式加入时不作为激酶的底物，但在Triton存在时起作用。在后一种形式中，它还能在内源性底物酶耗尽后恢复激酶活性。内源性磷脂酰肌醇生成的二磷酸肌醇在完整膜内保持相当稳定，而在洗涤剂的存在下其降解明显增强。本研究表明，大鼠肝脏中的磷脂酰肌醇激酶在高尔基体中高度富集，可以用非离子洗涤剂溶解和测定。
The phosphorylation of phosphatidylinositol in subcellular fractions from rat liver has been examined. Fractions enriched in Golgi showed by far the highest specific activity while a plasma membrane fraction depleted in Golgi, as well as rough microsomes, mitochondria, and particle-free supernatant had much lower activity. The product formed from [gamma-32P]ATP and endogenous or exogenously added phosphatidylinositol was predominantly diphosphoinositide with no more than 5% triphosphoinositide. The phosphatidylinositol kinase showed a broad pH optimum with peak activity around pH 7.8. The kinase reaction was not inhibited by the detergent Triton X-100, except at very high concentration, while it was severely inhibited by digitonin. Exogenous phosphatidylinositol did not serve as substrate for the kinase when added in the form of sonicated vesicles, but did so in the presence of Triton. In the latter form it also restored kinase activity after enzymatic depletion of endogenous substrate. The diphosphoinositide formed from endogenous phosphatidylinositol remained fairly stable in the intact membrane, while its degradation was enhanced significantly in the presence of detergent. This study indicates that the phosphatidylinositol kinase in rat liver is highly enriched in the Golgi and suggests that it can be solubilized and assayed by the use of a nonionic detergent.