Liteplo R G, Sribney M
Can J Biochem. 1980 Oct;58(10):871-7. doi: 10.1139/o80-121.
GTP has been found to markedly enhance the formation of CDP-diacylglycerol in rat liver microsomes. Neither GDP, GMP nor the nonhydrolyzable analogues of GTP increased the synthesis of the liponucleotide. The GTP stimulation of phosphatidate cytidylyltransferase activity is inhibited by EDTA and NaF. GTP enhances the activity of the enzyme in a concentration-, time-, and temperature-dependent manner and preincubation of rat liver microsomes with GTP produces a persistently activated phosphatidate cytidylyltransferase. GTP reduces the Km for phosphatidic acid, but has no effect on either the Km for CTP or the Vmax of the reaction. GTP, by stimulating the activity of the phosphatidate cytidylyltransferase, enhances the formation of phosphatidylinositol from CTP, phosphatidic acid, and inositol. Evidence is presented suggesting that the mechanism by which GTP stimulates the activity of the phosphatidate cytidylyltransferase involves a covalent modification of the enzyme itself or a protein intimately associated with the phosphatidate cytidylyltransferase.
已发现鸟苷三磷酸（GTP）能显著增强大鼠肝脏微粒体中CDP - 二酰甘油的形成。鸟苷二磷酸（GDP）、鸟苷一磷酸（GMP）以及GTP的不可水解类似物均未增加脂核苷酸的合成。GTP对磷脂酸胞苷转移酶活性的刺激作用受到乙二胺四乙酸（EDTA）和氟化钠（NaF）的抑制。GTP以浓度、时间和温度依赖性方式增强该酶的活性，并且用GTP对大鼠肝脏微粒体进行预孵育会产生持续激活的磷脂酸胞苷转移酶。GTP降低了对磷脂酸的米氏常数（Km），但对CTP的Km或反应的最大反应速度（Vmax）均无影响。GTP通过刺激磷脂酸胞苷转移酶的活性，增强了由CTP、磷脂酸和肌醇形成磷脂酰肌醇的过程。有证据表明，GTP刺激磷脂酸胞苷转移酶活性的机制涉及该酶自身或与磷脂酸胞苷转移酶紧密相关的一种蛋白质的共价修饰。
