Fargin A, Yamamoto K, Cotecchia S, Goldsmith P K, Spiegel A M, Lapetina E G, Caron M G, Lefkowitz R J
Department of Medicine, Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710.
Cell Signal. 1991;3(6):547-57. doi: 10.1016/0898-6568(91)90031-o.
The cloned 5-HT1A receptor, stably expressed in HeLa cells, has been shown to mediate the effects of 5-hydroxytryptamine (5-HT) to inhibit cAMP formation and to stimulate the hydrolysis of phosphatidylinositol. Both responses were found to be pertussis toxin sensitive. We have examined these two responses in membranes derived from these cells and show that the 5-HT1A receptor can directly regulate the activity of adenylyl cyclase and phospholipase C in response to agonist. In order to examine whether the same or distinct guanine nucleotide-binding regulatory protein(s) (G protein) are involved in these two signal transduction pathways, we used anti-peptide antibodies recognizing the alpha-subunits of Gi1, Gi2, Gi3 as specific tools, since these pertussis toxin substrates are expressed in HeLa cells. These antibodies have previously been shown to prevent receptor-G protein coupling by binding to the regions of G proteins which are putatively involved in interaction with receptors. Our results indicate that the Gi proteins, but preferentially Gi3, mediate the effects of 5-HT both to inhibit adenylyl cyclase and to stimulate phospholipase C. These findings demonstrate that the same receptor interacting with the same G protein can regulate several distinct effector molecules.
在HeLa细胞中稳定表达的克隆5-HT1A受体，已被证明可介导5-羟色胺（5-HT）抑制环磷酸腺苷（cAMP）形成及刺激磷脂酰肌醇水解的作用。这两种反应均被发现对百日咳毒素敏感。我们在源自这些细胞的膜中检测了这两种反应，并表明5-HT1A受体可响应激动剂直接调节腺苷酸环化酶和磷脂酶C的活性。为了研究这两种信号转导途径中是否涉及相同或不同的鸟嘌呤核苷酸结合调节蛋白（G蛋白），我们使用了识别Gi1、Gi2、Gi3α亚基的抗肽抗体作为特异性工具，因为这些百日咳毒素底物在HeLa细胞中表达。这些抗体先前已被证明可通过结合G蛋白中假定参与与受体相互作用的区域来阻止受体-G蛋白偶联。我们的结果表明，Gi蛋白，尤其是Gi3，介导了5-HT抑制腺苷酸环化酶和刺激磷脂酶C的作用。这些发现表明，与同一G蛋白相互作用的同一受体可调节几种不同的效应分子。
