Jackman G P, Bobik A
Alfred Hospital, Prahran, Australia.
Biochem Pharmacol. 1989 Apr 1;38(7):1091-5. doi: 10.1016/0006-2952(89)90253-0.
We have investigated whether the greater ability of forskolin to activate adenylate cyclase (EC 4.6.1.1) from rat heart compared with rat lung is due to interactions between G-proteins and catalytic units, isoforms of catalytic units or membrane-protein interactions. Interactions between Gs and catalytic units were found to be similar in both tissues with 10 microM Gpp(NH)p increasing activity up to 5-fold. While MnCl2 increased the response of the lung enzyme to forskolin, it reduced the response of the cardiac enzyme and uncoupled Gs from the cardiac catalytic units indicating that Gs interactions potentiate the response to forskolin. After enzyme solubilisation with n-octyl-beta-D-glucopyranoside, the response to forskolin was identical in heart and lung whether assayed with magnesium or manganese chloride, and not significantly different from the heart membrane enzyme. Overall, the results show that the relatively poor response of lung adenylate cyclase to forskolin is due to specific inhibitory interactions between the enzyme and lung membrane constituents.
我们研究了与大鼠肺相比，福斯高林激活大鼠心脏腺苷酸环化酶（EC 4.6.1.1）能力更强是否归因于G蛋白与催化亚基之间的相互作用、催化亚基的同工型或膜蛋白相互作用。在两种组织中均发现Gs与催化亚基之间的相互作用相似，10 microM Gpp(NH)p可使活性增加至5倍。虽然MnCl2增加了肺酶对福斯高林的反应，但它降低了心脏酶的反应，并使Gs与心脏催化亚基解偶联，表明Gs相互作用增强了对福斯高林的反应。在用正辛基-β-D-吡喃葡萄糖苷溶解酶后，无论用氯化镁还是氯化锰测定，心脏和肺对福斯高林的反应均相同，且与心脏膜酶无显著差异。总体而言，结果表明肺腺苷酸环化酶对福斯高林反应相对较差是由于该酶与肺膜成分之间存在特异性抑制相互作用。
