Kobilka B K, Frielle T, Dohlman H G, Bolanowski M A, Dixon R A, Keller P, Caron M G, Lefkowitz R J
J Biol Chem. 1987 May 25;262(15):7321-7.
The beta 2-adrenergic receptor is the first adenylate cyclase-coupled receptor to be cloned. We provide here a detailed characterization of its complete gene in both the human and hamster which reveals several unusual and provocative features. The genes are present in a single copy, are intronless, and are bounded by homologous 18-bp (base pair) direct repeats. These findings suggest that the beta 2-adrenergic receptor may have arisen as a processed gene for another related gene. Genomic Southern blots done at reduced stringency in fact reveal additional weak signals. The human and hamster gene sequences 5' to the principal site of transcription initiation are highly homologous and share many characteristics of promoters for housekeeping genes. Moreover, there is present in the human genome a long (777 bp) open reading frame which is in frame with the beta-adrenergic receptor coding block and which ends only 234 bp 5' to the initiator methionine of the receptor. An unusual cDNA has been found, transcribed from a putative second more 5' promoter which contains the 5' half of the beta-adrenergic receptor as well as 1065-bp 5' to the receptor coding region, including the entire upstream long open reading frame (sufficient to encode a putative protein of Mr approximately 28,000).
β2 - 肾上腺素能受体是第一个被克隆的与腺苷酸环化酶偶联的受体。我们在此提供了其在人类和仓鼠中完整基因的详细特征，揭示了几个不同寻常且引人深思的特点。这些基因以单拷贝形式存在，无内含子，并由同源的18个碱基对的直接重复序列界定。这些发现表明β2 - 肾上腺素能受体可能是作为另一个相关基因的加工基因出现的。实际上，在较低严谨度下进行的基因组Southern杂交揭示了额外的微弱信号。转录起始主要位点5'端的人类和仓鼠基因序列高度同源，并具有许多管家基因启动子的特征。此外，人类基因组中存在一个长777 bp的开放阅读框，它与β - 肾上腺素能受体编码区读码框一致，且在受体起始甲硫氨酸5'端仅234 bp处结束。已发现一个不寻常的cDNA，它由一个假定的更靠5'端的第二个启动子转录而来，该启动子包含β - 肾上腺素能受体的5'半部分以及受体编码区5'端1065 bp，包括整个上游长开放阅读框（足以编码一个约28,000 Mr的假定蛋白质）。
