Molecular cloning of a mammalian serotonin receptor that activates adenylate cyclase.
Molecular cloning of a mammalian serotonin receptor that activates adenylate cyclase.
复制标题
激活腺苷酸环化酶的哺乳动物血清素受体的分子克隆。
作者：
J. Plassat;N. Amlaiky;R. Hen
5-羟色胺通过激活与各种效应系统偶联的多种受体来调节广泛的生理功能。使用基于5-羟色胺（5-HT）受体之间的氨基酸序列同源性的策略，我们已经从小鼠脑文库中分离出编码新的5-HT受体，5-HTx，激活腺苷酸环化酶的cDNA。氨基酸序列比较显示，5-HTx受体是以前克隆的5-HT受体的远亲，与5-HTdro 1受体同源性最高（42%），这是一种与腺苷酸环化酶正偶联的果蝇5-HT受体。在瞬时表达5-HT x受体的COS-7细胞中，5-HT诱导cAMP水平增加，其具有剂量依赖性和饱和性（EC 50 = 45 nM）。激动剂显示出以下效力等级顺序：5-羧酰胺色胺> 5-甲氧基色胺> 5-HT > RU 24969 > 8-羟基-2-（二正丙基氨基）四氢萘。抑制5-HT兴奋作用的最有效的拮抗剂是麦角新碱、甲硫替平、美舒麦角碱、甲麦角林、氯氮平、麦角胺和（+）-丁他拉莫。表达5-HTx受体的COS-7细胞膜显示单一的[3 H]5-HT饱和结合位点。各种药物取代[3 H]5-HT结合的效力顺序与cAMP实验中获得的顺序相似。该受体的药理学特征不对应于任何经典5-HT受体亚型的特征。5-HTx mRNA的表达在脑干中最高，在前脑、小脑、肠和心脏中较低。因此，5-HTx受体可能与5-HT 1样受体相对应，5-HT 1样受体已被证明可诱导猪腔静脉和豚鼠回肠的舒张以及猫心脏的心动过速。5-HTx受体对安定药如（+）-丁他拉莫和氯氮平的高亲和力也表明该受体可能在某些神经精神障碍中起作用。
Serotonin modulates a wide range of physiological functions by activating multiple receptors, which are coupled to various effector systems. Using a strategy based on amino acid sequence homology between 5-hydroxytryptamine (5-HT) receptors, we have isolated from a mouse brain library a cDNA encoding a new 5-HT receptor, 5-HTx, that activates adenylate cyclase. Amino acid sequence comparisons revealed that the 5-HTx receptor was a distant relative of previously cloned 5-HT receptors, with the highest percentage of homology (42%) being with the 5-HTdro1 receptor, a Drosophila 5-HT receptor positively coupled to adenylate cyclase. In COS-7 cells transiently expressing the 5-HTx receptor, 5-HT induced an increase in cAMP levels that was dose dependent and saturable (EC50 = 45 nM). Agonists displayed the following rank order of potencies: 5-carboxamidotryptamine > 5-methoxytryptamine > 5-HT > RU 24969 > 8-hydroxy-2-(di-n-propylamino)tetralin. The most efficient antagonists in inhibiting the stimulatory effect of 5-HT were methysergide, methiothepin, mesulergine, metergoline, clozapine, ergotamine, and (+)-butaclamol. Membranes of COS-7 cells expressing the 5-HTx receptor displayed a single saturable binding site for [3H]5-HT. The order of potencies of various drugs in displacing [3H]5-HT binding was similar to the order obtained in cAMP experiments. The pharmacological profile of this receptor does not correspond to the profile of any of the classic 5-HT receptor subtypes. Expression of 5-HTx mRNA was highest in brainstem and lower in forebrain, cerebellum, intestine, and heart. The 5-HTx receptor might therefore correspond to 5-HT1-like receptors that have been shown to induce relaxation in porcine vena cava and guinea pig ileum as well as tachycardia in cat heart. The high affinity of the 5-HTx receptor for neuroleptic agents such as (+)-butaclamol and clozapine suggests also that this receptor might play a role in certain neuropsychiatric disorders.