Martin J M, Liles W C, Nathanson N M
Department of Pharmacology, University of Washington, Seattle 98195.
Brain Res. 1988 Jul 12;455(2):370-6. doi: 10.1016/0006-8993(88)90097-2.
Islet-activating protein (IAP) was used to investigate the role of the guanosine triphosphate binding proteins Gi and/or Go in muscarinic acetylcholine receptor-mediated responses in neuroblastoma cells (clone N1E-115). Incubation of intact cells for 24 h with 20 ng/ml IAP resulted in inhibition of subsequent IAP catalyzed incorporation of [32P]ADP-ribose into a membrane protein doublet of molecular weight 40,000 (Gi alpha and Go alpha). IAP treatment fully blocked muscarinic receptor-mediated inhibition of cAMP accumulation. Incubation of intact cells with carbachol for 8 h resulted in the concentration dependent loss of membrane muscarinic receptor. Pretreatment of cells with IAP prior to carbachol exposure partially blocked the subsequent decrease in receptor number. Pretreatment of cells with IAP had no effect on the ability of carbachol to stimulate phosphoinositide hydrolysis in neuroblastoma cells. Thus, while the guanosine triphosphate binding proteins Gi and/or Go are involved in coupling the muscarinic receptor to some of the physiological responses in these cells, it is clear that activation of phospholipase C by the muscarinic receptor is a Gi/Go independent response.
胰岛激活蛋白（IAP）被用于研究三磷酸鸟苷结合蛋白Gi和/或Go在神经母细胞瘤细胞（克隆N1E-115）毒蕈碱型乙酰胆碱受体介导的反应中的作用。将完整细胞与20 ng/ml IAP孵育24小时，导致随后IAP催化的[32P]ADP-核糖掺入分子量为40,000的膜蛋白双峰（Giα和Goα）受到抑制。IAP处理完全阻断了毒蕈碱受体介导的cAMP积累的抑制作用。将完整细胞与卡巴胆碱孵育8小时，导致膜毒蕈碱受体浓度依赖性丢失。在卡巴胆碱暴露前用IAP预处理细胞，部分阻断了随后受体数量的减少。用IAP预处理细胞对卡巴胆碱刺激神经母细胞瘤细胞中磷酸肌醇水解的能力没有影响。因此，虽然三磷酸鸟苷结合蛋白Gi和/或Go参与了毒蕈碱受体与这些细胞中某些生理反应的偶联，但很明显，毒蕈碱受体激活磷脂酶C是一种不依赖Gi/Go的反应。
