Murayama T, Katada T, Ui M
Arch Biochem Biophys. 1983 Mar;221(2):381-90. doi: 10.1016/0003-9861(83)90157-1.
Guanine nucleotide regulation of membrane adenylate cyclase activity was uniquely modified after exposure of 3T3 mouse fibroblasts to low concentrations of islet-activating protein (IAP), pertussis toxin. The action of IAP, which occurred after a lag time, was durable and irreversible, and was associated with ADP-ribosylation of a membrane Mr = 41,000 protein. GTP, but not Gpp(NH)p, was more efficient and persistent in activating adenylate cyclase in membranes from IAP-treated cells than membranes from control cells. GTP and Gpp(NH)p caused marked inhibition of adenylate cyclase when the enzyme system was converted to its highly activated state by cholera toxin treatment or fluoride addition, presumably as a result of their interaction with the specific binding protein which is responsible for inhibition of adenylate cyclase. This inhibition was totally abolished by IAP treatment of cells, making it very likely that IAP preferentially modulates GTP inhibitory responses, thereby increasing GTP-dependent activation and negating GTP-mediated inhibition of adenylate cyclase.
将3T3小鼠成纤维细胞暴露于低浓度的胰岛激活蛋白（IAP）即百日咳毒素后，鸟嘌呤核苷酸对膜腺苷酸环化酶活性的调节发生了独特的改变。IAP的作用在一段延迟时间后出现，持久且不可逆，并且与一种分子量为41,000的膜蛋白的ADP核糖基化有关。与对照细胞的膜相比，GTP而非Gpp(NH)p在激活IAP处理细胞的膜中的腺苷酸环化酶方面更有效且更持久。当通过霍乱毒素处理或添加氟化物使酶系统转变为高激活状态时，GTP和Gpp(NH)p会导致腺苷酸环化酶受到显著抑制，推测这是它们与负责抑制腺苷酸环化酶的特异性结合蛋白相互作用的结果。细胞经IAP处理后，这种抑制作用完全消除，这很可能是因为IAP优先调节GTP的抑制反应，从而增强GTP依赖性激活并消除GTP介导的腺苷酸环化酶抑制作用。
