Richert N D, Ryan R J
Proc Natl Acad Sci U S A. 1977 Nov;74(11):4857-61. doi: 10.1073/pnas.74.11.4857.
Various serine proteases (e.g., trypsin, alpha-chymotrypsin, Pronase, and subtilisin) stimulate adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] activity in a membrane-enriched fraction of the rat ovary. Maximum stimulation is observed at protease concentrations ranging from 3 to 10 mug/ml. Higher protease concentrations inhibit ovarian adenylate cyclase in a dose-dependent manner. Protease stimulation causes a 6- to 8-fold increase in adenylate cyclase activity, which is comparable to the stimulation observed with human chorionic gonadotropin. Combinations of trypsin plus hormone or trypsin plus NaF stimulate ovarian adenylate cyclase activity to a greater extent than does any one of these alone. The mechanism of protease stimulation of adenylate cyclase involves limited proteolysis because zymogen precursors fail to activate the cyclase as does trypsin pretreated with trypsin inhibitors. Unlike cholera toxin, the serine protease stimulation is immediate (within the first 5 min) and requires no additional factors (e.g., NAD(+)). It is unlikely that protease stimulation of adenylate cyclase results from a proteolytic modification of the hormone receptor on the cell surface, because of the additive effects noted above and because protease stimulation is also observed in ovaries desensitized to hormone that lack this hormone receptor. Results with Lubrol-treated membranes also suggest that proteolytic enzymes do not directly activate the catalytic subunit of the cyclase or unmask new catalytic sites because the protease effect (like hormonal stimulation) is abolished by the detergent, whereas fluoride stimulation is enhanced. Other data suggest that serine protease and chorionic gonadotropin stimulation of adenylate cyclase result from activation of a membrane protease that then regulates adenylate cyclase in the ovary.
多种丝氨酸蛋白酶（如胰蛋白酶、α-糜蛋白酶、链霉蛋白酶和枯草杆菌蛋白酶）可刺激大鼠卵巢富含膜的部分中的腺苷酸环化酶[ATP 焦磷酸裂解酶（环化），EC 4.6.1.1]活性。在蛋白酶浓度为 3 至 10μg/ml 范围内观察到最大刺激作用。更高的蛋白酶浓度以剂量依赖的方式抑制卵巢腺苷酸环化酶。蛋白酶刺激可使腺苷酸环化酶活性增加 6 至 8 倍，这与人绒毛膜促性腺激素所观察到的刺激作用相当。胰蛋白酶加激素或胰蛋白酶加 NaF 的组合比单独使用其中任何一种更能刺激卵巢腺苷酸环化酶活性。蛋白酶刺激腺苷酸环化酶的机制涉及有限的蛋白水解作用，因为酶原前体不能像用胰蛋白酶抑制剂预处理的胰蛋白酶那样激活环化酶。与霍乱毒素不同，丝氨酸蛋白酶刺激是即时的（在最初 5 分钟内），且不需要其他因素（如 NAD(+)）。蛋白酶刺激腺苷酸环化酶不太可能是由于细胞表面激素受体的蛋白水解修饰导致的，这是因为上述的相加作用，并且在对缺乏该激素受体的激素脱敏的卵巢中也观察到了蛋白酶刺激作用。用 Lubrol 处理的膜的实验结果还表明，蛋白水解酶不会直接激活环化酶的催化亚基或暴露新的催化位点，因为蛋白酶的作用（如激素刺激）会被去污剂消除，而氟化物刺激则会增强。其他数据表明，丝氨酸蛋白酶和绒毛膜促性腺激素对腺苷酸环化酶的刺激是由一种膜蛋白酶的激活引起的，然后该膜蛋白酶调节卵巢中的腺苷酸环化酶。
