Lomasney J W, Cotecchia S, Lorenz W, Leung W Y, Schwinn D A, Yang-Feng T L, Brownstein M, Lefkowitz R J, Caron M G
Department of Pathology, Duke University Medical Center, Durham, North Carolina 27710.
J Biol Chem. 1991 Apr 5;266(10):6365-9.
Pharmacological and molecular cloning studies have demonstrated heterogeneity of alpha 1-adrenergic receptors. We have now cloned two alpha 1-adrenergic receptors from a rat cerebral cortex cDNA library, using the hamster alpha 1B-adrenergic receptor as a probe. The deduced amino acid sequence of clone RA42 encodes a protein of 560 amino acids whose putative topology is similar to that of the family of G-protein-coupled receptors. The primary structure though most closely resembles that of an alpha 1-adrenergic receptor, having approximately 73% amino acid identity in the putative transmembrane domains with the previously isolated hamster alpha 1B receptor. Analysis of the ligand binding properties of RA42 expressed in COS-7 cells with a variety of adrenergic ligands demonstrates a unique alpha 1-adrenergic receptor pharmacology. High affinity for the antagonist WB4101 and agonists phenylephrine and methoxamine suggests that cDNA RA42 encodes the alpha 1A receptor subtype. Northern blot analysis of various rat tissues also shows the distribution expected of the alpha 1A receptor subtype with abundant expression in vas deferens followed by hippocampus, cerebral cortex, aorta, brainstem, heart and spleen. The second alpha 1-adrenergic receptor cloned represents the rat homolog of the hamster alpha 1B subtype. Expression of mRNA for this receptor is strongly detected in liver followed by heart, cerebral cortex, brain stem, kidney, lung, and spleen. This study provides definitive evidence for the existence of three alpha 1-adrenergic receptor subtypes.
药理学和分子克隆研究已证明α1 - 肾上腺素能受体具有异质性。我们现在使用仓鼠α1B - 肾上腺素能受体作为探针，从大鼠大脑皮质cDNA文库中克隆出了两种α1 - 肾上腺素能受体。克隆体RA42推导的氨基酸序列编码一个由560个氨基酸组成的蛋白质，其推测的拓扑结构与G蛋白偶联受体家族相似。尽管其一级结构与α1 - 肾上腺素能受体最为相似，在推测的跨膜结构域中与先前分离的仓鼠α1B受体具有约73%的氨基酸同一性。用多种肾上腺素能配体分析在COS - 7细胞中表达的RA42的配体结合特性，显示出一种独特的α1 - 肾上腺素能受体药理学特征。对拮抗剂WB4101以及激动剂去氧肾上腺素和甲氧明具有高亲和力，这表明cDNA RA42编码α1A受体亚型。对各种大鼠组织的Northern印迹分析也显示出α1A受体亚型预期的分布情况，在输精管中大量表达，其次是海马体、大脑皮质、主动脉、脑干、心脏和脾脏。克隆出的第二种α1 - 肾上腺素能受体代表仓鼠α1B亚型的大鼠同源物。在肝脏中强烈检测到该受体的mRNA表达，其次是心脏、大脑皮质、脑干、肾脏、肺和脾脏。这项研究为三种α1 - 肾上腺素能受体亚型的存在提供了确凿证据。
