Demchyshyn L L, Sugamori K S, Lee F J, Hamadanizadeh S A, Niznik H B
Department of Psychiatry, University of Toronto, Ontario, Canada.
J Biol Chem. 1995 Feb 24;270(8):4005-12. doi: 10.1074/jbc.270.8.4005.
Three genomic clones encoding dopamine D1-like receptors were isolated from the avian species Gallus domesticus. Two of these genes encode proteins of 451 and 488 amino acids, which, based on deduced amino acid sequence identity and homology of exhibited pharmacological profiles, appear to be species homologs of mammalian and vertebrate D1/D1A and D5/D1B receptors, respectively. The third genomic clone, termed D1D, encodes a protein of 445 amino acids displaying a deduced amino acid sequence identity within putative transmembrane domains of 75% to mammalian D1/D1A and 77% to D5/D1B receptors with overall sequence homologies of only 49% and 46%, respectively. Membranes from COS-7 cells transfected with D1D DNA bound [3H]SCH-23390 in a saturable manner with high affinity (approximately 300 pM) and with a pharmacological profile clearly indicative of a dopamine D1-like receptor. The D1D receptor exhibited affinities for 6,7-dihydroxy-2-aminotetralin and dopamine 10-fold higher than D1/D1A receptors, characteristic of the D5/D1B receptor subfamily. In contrast, the D1D receptor bound dopaminergic agents, such as SKF-38393, apomorphine, pergolide, and lisuride, with affinities 10-fold higher than other cloned mammalian or vertebrate D1A/D1B receptor subtypes, while both clozapine and haloperidol displayed considerably lower affinity for the D1D receptor. Based on the low overall amino acid sequence identity (54%) and unique pharmacological profile, the avian dopamine D1D receptor does not appear to be a species homolog of the recently cloned vertebrate D1C receptor (Sugamori, K.S., Demchyshyn, L. L., Chung, M., and Niznik, H. B. (1994) Proc. Natl. Acad. Sci. U.S.A. 91, 10536-10540). As with all cloned mammalian and vertebrate D1-like receptors, the D1D receptor stimulates adenylate cyclase activity in the presence of dopamine or SKF-82526. Northern blot analysis reveals the selective expression of both avian D1D and D1A receptor mRNAs only in brain with the D1B receptor more widely distributed and localized in tissues such as brain, kidney, and spleen. The isolation of four distinct vertebrate dopamine D1 receptor subtypes suggests the existence of additional mammalian D1 like receptor genes that may account for the observed pharmacological and biochemical multiplicity of dopamine D1-like receptor mediated events.
从家鸡这一鸟类物种中分离出了三个编码多巴胺D1样受体的基因组克隆。其中两个基因编码的蛋白质分别含有451和488个氨基酸，根据推导的氨基酸序列同一性以及所表现出的药理学特征的同源性，它们似乎分别是哺乳动物和脊椎动物D1/D1A以及D5/D1B受体的物种同源物。第三个基因组克隆，称为D1D，编码一个含有445个氨基酸的蛋白质，在假定的跨膜结构域内，其推导的氨基酸序列同一性与哺乳动物D1/D1A受体为75%，与D5/D1B受体为77%，而整体序列同源性分别仅为49%和46%。用D1D DNA转染的COS-7细胞的膜以高亲和力（约300 pM）以可饱和方式结合[3H]SCH-23390，并且药理学特征清楚地表明是一种多巴胺D1样受体。D1D受体对6,7-二羟基-2-氨基四氢萘和多巴胺的亲和力比D1/D1A受体高10倍，这是D5/D1B受体亚家族的特征。相比之下，D1D受体与多巴胺能药物如SKF-38393、阿扑吗啡、培高利特和利苏力特结合的亲和力比其他克隆的哺乳动物或脊椎动物D1A/D1B受体亚型高10倍，而氯氮平和氟哌啶醇对D1D受体的亲和力则低得多。基于低的整体氨基酸序列同一性（54%）和独特的药理学特征，禽类多巴胺D1D受体似乎不是最近克隆的脊椎动物D1C受体（Sugamori, K.S., Demchyshyn, L. L., Chung, M., and Niznik, H. B. (1994) Proc. Natl. Acad. Sci. U.S.A. 91, 10536 - 10540）的物种同源物。与所有克隆的哺乳动物和脊椎动物D1样受体一样，D1D受体在多巴胺或SKF-82526存在的情况下刺激腺苷酸环化酶活性。Northern印迹分析显示，禽类D1D和D1A受体mRNA仅在脑中选择性表达，而D1B受体分布更广泛，定位于脑、肾和脾等组织。四种不同的脊椎动物多巴胺D1受体亚型被分离出来，这表明可能存在其他哺乳动物D1样受体基因，它们可能解释了多巴胺D1样受体介导的事件中观察到的药理学和生化多样性。
