Friedman Y, Wilger J, Crowell D, Burke G
Endocrinology. 1983 May;112(5):1674-9. doi: 10.1210/endo-112-5-1674.
Trypsin, chymotrypsin, and papain stimulate basal adenylate cyclase activity in bovine thyroid plasma membranes in a dose-related, albeit biphasic, fashion. Each of the proteases enhanced TSH-stimulated adenylate cyclase activity over basal activity. The proteases also enhanced GTP-, guanosine 5'-(beta, gamma-imidotriphosphate)-, prostaglandin E1-, and cholera toxin-stimulated adenylate cyclase to varying degrees. Fluoride-stimulated activity was enhanced by chymotrypsin and papain, but not by trypsin. When Mn++ was substituted for Mg++ in the adenylate cyclase assay, no stimulation by the proteases were observed. To see if endogenous membrane proteases are required for optimal thyroid adenylate cyclase response to TSH and other stimulators, studies were performed using the protease inhibitors tosylamide 2-phenylethyl-chloromethyl ketone (TPCK) and p-tosyl-L-arginine methyl ester (TAME), inhibitors of chymotrypsin and trypsin, respectively. TPCK (0.15 mM) had no effect on basal adenylate cyclase activity, but did inhibit TSH-, trypsin-, and chymotrypsin-stimulated activities by approximately 90%. Guanosine 5'-(beta, gamma-imido) triphosphate- as well as cholera toxin-stimulated activities were inhibited by approximately 50%, whereas prostaglandin E1- and fluoride-stimulated activities were inhibited by approximately 25%. TAME (6 mM) produced similar results, except that no effect on fluoride activity was seen, while basal activity was inhibited by approximately 20%. Thus, various serine proteases augment both basal and hormone-stimulated adenylate cyclase in bovine thyroid. Since both trypsin- and chymotrypsin-stimulated as well as TSH-induced enzyme activities were inhibited by TPCK and TAME, it would appear that augmentation of thyroid adenylate cyclase activity may, in part, result from stimulation of endogenous proteases.
胰蛋白酶、胰凝乳蛋白酶和木瓜蛋白酶以剂量相关的方式刺激牛甲状腺质膜中的基础腺苷酸环化酶活性，尽管这种方式呈双相性。每种蛋白酶都使促甲状腺激素（TSH）刺激的腺苷酸环化酶活性高于基础活性。这些蛋白酶还不同程度地增强了鸟苷三磷酸（GTP）、5'-（β，γ-亚氨基三磷酸）鸟苷、前列腺素E1和霍乱毒素刺激的腺苷酸环化酶活性。胰凝乳蛋白酶和木瓜蛋白酶增强了氟化物刺激的活性，但胰蛋白酶没有。当在腺苷酸环化酶测定中用锰离子（Mn++）替代镁离子（Mg++）时，未观察到蛋白酶的刺激作用。为了确定甲状腺腺苷酸环化酶对TSH和其他刺激物的最佳反应是否需要内源性膜蛋白酶，使用蛋白酶抑制剂对甲苯磺酰胺2-苯乙基氯甲基酮（TPCK）和对甲苯磺酰-L-精氨酸甲酯（TAME）进行了研究，它们分别是胰凝乳蛋白酶和胰蛋白酶的抑制剂。TPCK（0.15 mM）对基础腺苷酸环化酶活性没有影响，但确实使TSH、胰蛋白酶和胰凝乳蛋白酶刺激的活性降低了约90%。5'-（β，γ-亚氨基）三磷酸鸟苷以及霍乱毒素刺激的活性降低了约50%，而前列腺素E1和氟化物刺激的活性降低了约25%。TAME（6 mM）产生了类似的结果，只是未观察到对氟化物活性的影响，而基础活性降低了约20%。因此，各种丝氨酸蛋白酶增强了牛甲状腺中基础的和激素刺激的腺苷酸环化酶活性。由于TPCK和TAME抑制了胰蛋白酶和胰凝乳蛋白酶刺激的以及TSH诱导的酶活性，似乎甲状腺腺苷酸环化酶活性的增强可能部分源于内源性蛋白酶的刺激。
