Meng F, Xie G X, Chalmers D, Morgan C, Watson S J, Akil H
Mental Health Research Institute, University of Michigan, Ann Arbor 48109.
Neurochem Res. 1994 May;19(5):613-21. doi: 10.1007/BF00971338.
A full-length complementary DNA (cDNA) clone encoding the guinea pig brain A2 adenosine receptor has been isolated by polymerase chain reaction (PCR) and low-stringency-hybridization screening of a guinea pig brain cDNA library. This cDNA contains a long open reading frame encoding a 409-amino acid-residue protein which is highly homologous to the A2 adenosine receptors previously cloned from other species. Hydrophobicity analysis of the deduced protein sequence reveals seven hydrophobic regions, characteristic of a member of the G-protein-coupled receptor superfamily. Radioligand binding assay and functional (GTPase and cAMP) assays of the receptor, transiently expressed in mammalian cells, demonstrate typical characteristics of the A2 type adenosine receptor. The messenger RNA (mRNA) of this A2 receptor is found in the brain, heart, kidney and spleen. Receptor autoradiography with [3H]CGS21680, a specific A2 agonist, and in situ hybridization with A2 cRNA probe in guinea pig brain indicate that the receptor is expressed exclusively in the caudate nucleus. The pharmacological profile and anatomical distribution of this receptor indicate that it is of the A2a subtype. This work represents the first cloning of an A2a receptor in a rodent species, offers a complete pharmacological characterization of the receptor and provides an anatomical comparison between binding profile and gene expression of the receptor.
通过聚合酶链反应（PCR）以及对豚鼠脑cDNA文库进行低严谨度杂交筛选，分离出了编码豚鼠脑A2腺苷受体的全长互补DNA（cDNA）克隆。该cDNA包含一个长开放阅读框，编码一个409个氨基酸残基的蛋白质，该蛋白质与先前从其他物种克隆的A2腺苷受体高度同源。对推导的蛋白质序列进行疏水性分析，揭示出七个疏水区，这是G蛋白偶联受体超家族成员的特征。对在哺乳动物细胞中瞬时表达的该受体进行放射性配体结合试验和功能（GTP酶和cAMP）试验，证明其具有A2型腺苷受体的典型特征。在脑、心脏、肾脏和脾脏中发现了这种A2受体的信使RNA（mRNA）。用特异性A2激动剂[3H]CGS21680进行受体放射自显影，以及用A2 cRNA探针在豚鼠脑中进行原位杂交，结果表明该受体仅在尾状核中表达。该受体的药理学特征和解剖分布表明它属于A2a亚型。这项工作代表了啮齿类动物中A2a受体的首次克隆，提供了该受体完整的药理学特征，并对受体的结合特征和基因表达进行了解剖学比较。
