Merida I, Mato J M
Biochim Biophys Acta. 1987 Apr 2;928(1):92-7. doi: 10.1016/0167-4889(87)90089-9.
Addition of insulin to isolated rat hepatocytes prelabeled with [32P]phosphate inhibited glucagon-dependent phospholipid methyltransferase phosphorylation and activation. Insulin alone had no effect on either the phosphorylation of the enzyme or on its activity. The effect of insulin on glucagon-dependent phospholipid methyltransferase phosphorylation was dose-dependent and occurred at physiological doses of the hormone (10(-11)-10(-10) M). Analysis of 32P-labeled peptides after digestion with trypsin revealed only one site of phosphorylation regulated by glucagon (10(-8) M) in isolated rat hepatocytes. This site, as analyzed by HPLC and thin-layer chromatography, coincided with that phosphorylated by the cAMP-dependent protein kinase using purified rat liver phospholipid methyltransferase.
向预先用[32P]磷酸盐标记的离体大鼠肝细胞中添加胰岛素，可抑制胰高血糖素依赖性磷脂甲基转移酶的磷酸化和激活。单独使用胰岛素对该酶的磷酸化或其活性均无影响。胰岛素对胰高血糖素依赖性磷脂甲基转移酶磷酸化的作用呈剂量依赖性，且在该激素的生理剂量（10^(-11)-10^(-10) M）下即可出现。用胰蛋白酶消化后对32P标记的肽段进行分析，结果显示在离体大鼠肝细胞中，只有一个受胰高血糖素（10^(-8) M）调节的磷酸化位点。经高效液相色谱法和薄层色谱法分析，该位点与使用纯化的大鼠肝脏磷脂甲基转移酶的cAMP依赖性蛋白激酶磷酸化的位点一致。
