Kelly K L, Wong E H, Jarett L
J Biol Chem. 1985 Mar 25;260(6):3640-4.
Treatment of isolated rat adipocytes with adrenocorticotropin (ACTH) caused a 1.5-fold increase in phospholipid methyltransferase activity within 5 min. This effect of ACTH was concentration-dependent with maximal activation at 2 milliunits/ml ACTH, and was reproduced by dibutyryl cyclic AMP. ACTH (2 milliunits/ml) caused an increase in the Vmax value of phospholipid methyltransferase without changing the Km for S-adenosyl-L-methionine. Insulin caused a concentration-dependent inhibition of both control and ACTH-stimulated phospholipid methyltransferase. Half-maximal inhibition by insulin was demonstrated with 5 microunits/ml insulin in control cells and with 25 microunits/ml insulin in ACTH-stimulated cells. The rapid and sensitive activation of adipocyte phospholipid methyltransferase by ACTH and inhibition by insulin are consistent with a role for this pathway in the hormonal response of the adipocyte.
用促肾上腺皮质激素（ACTH）处理分离的大鼠脂肪细胞，5分钟内磷脂甲基转移酶活性增加了1.5倍。ACTH的这种作用呈浓度依赖性，在2毫单位/毫升ACTH时激活作用最大，并且二丁酰环磷酸腺苷可重现这种作用。ACTH（2毫单位/毫升）使磷脂甲基转移酶的Vmax值增加，而不改变对S-腺苷-L-甲硫氨酸的Km值。胰岛素对对照和ACTH刺激的磷脂甲基转移酶均产生浓度依赖性抑制。在对照细胞中，5微单位/毫升胰岛素可产生半数最大抑制作用，在ACTH刺激的细胞中，25微单位/毫升胰岛素可产生半数最大抑制作用。ACTH对脂肪细胞磷脂甲基转移酶的快速且灵敏的激活作用以及胰岛素的抑制作用，与该途径在脂肪细胞激素反应中的作用一致。
