Richardson M C, Schulster D
Biochem J. 1973 Dec;136(4):993-8. doi: 10.1042/bj1360993.
A method has been developed for investigation of the effect of adrenocorticotrophic hormone (ACTH) on the state of activation of a cyclic AMP-dependent protein kinase within cells of the adrenal cortex. Enzyme activity was measured in terms of the quantity of (32)P transferred from [gamma-(32)P]ATP to histone under conditions in which bound cyclic AMP did not dissociate from the regulatory subunit of the protein kinase ACTH (1x10(-2)i.u./ml) caused a rapid and complete activation of the cyclic AMP-dependent protein kinase activity within 2min of hormone addition to the isolated cells. In response to a range of ACTH concentrations a sigmoid log dose-response curve for protein kinase activation was obtained, with half-maximal stimulation attained at about 1x10(-3)i.u./ml. However, some low doses of ACTH that elicited a marked (but submaximal) steroidogenic response failed to cause a clear stimulation of protein kinase activity in isolated adrenal cells. Theophylline (2mm) potentiated the effect of ACTH on protein kinase activity. The results implicate an important role for protein kinase in ACTH action on the adrenocortical cell.
已开发出一种方法，用于研究促肾上腺皮质激素（ACTH）对肾上腺皮质细胞内依赖环磷酸腺苷（cAMP）的蛋白激酶激活状态的影响。在结合的cAMP不会从蛋白激酶的调节亚基解离的条件下，通过测量从[γ-(32)P]ATP转移到组蛋白上的(32)P的量来测定酶活性。将ACTH（1×10(-2)国际单位/毫升）添加到分离的细胞中后，在2分钟内即可快速且完全激活依赖cAMP的蛋白激酶活性。对于一系列ACTH浓度，获得了蛋白激酶激活的S形对数剂量反应曲线，在约1×10(-3)国际单位/毫升时达到最大刺激的一半。然而，一些能引发显著（但未达到最大）类固醇生成反应的低剂量ACTH未能在分离的肾上腺细胞中引起蛋白激酶活性的明显刺激。茶碱（2毫摩尔）增强了ACTH对蛋白激酶活性的作用。结果表明蛋白激酶在ACTH对肾上腺皮质细胞的作用中起重要作用。
