Price S R, Murtagh J J, Tsuchiya M, Serventi I M, Van Meurs K P, Angus C W, Moss J, Vaughan M
Laboratory of Cellular Metabolism, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892.
Biochemistry. 1990 May 29;29(21):5069-76. doi: 10.1021/bi00473a011.
Go, a guanine nucleotide binding protein found predominantly in neural tissues, interacts in vitro with rhodopsin, muscarinic, and other receptors and has been implicated in the regulation of ion channels. Despite the virtual identity of reported cDNA sequences for the alpha subunit of Go (Go alpha), multiple molecular weight forms of mRNA have been identified in tissues from all species examined. To investigate the molecular basis for the size heterogeneity of Go alpha mRNAs, four cDNA clones were isolated from the same retinal lambda gt10 cDNA library that was used earlier to isolate lambda GO9, a clone encompassing the complete coding region of Go alpha. These clones were identified as Go alpha clones based on nucleotide sequence identity with lambda GO9 in the coding region; they diverge, however, from lambda GO9 in the 3'-untranslated region 28 nucleotides past the stop codon. An oligonucleotide probe complementary to a portion of the 3'-untranslated region of lambda GO9 that differs from the newly isolated clones hybridized with 3.0- and 4.0-kb mRNAs present in bovine brain and retina whereas a similar probe for the unique region of the new clones hybridized with a 4.0-kb mRNA in both tissues and with a 2.0-kb mRNA found predominantly in retina. A similar hybridization pattern was observed when brain poly(A+) RNA from other species was hybridized with the different 3'-untranslated region probes. It appears that differences in the 3'-untranslated regions could, in part, be the basis for the observed heterogeneity in Go alpha mRNAs.
Go是一种主要在神经组织中发现的鸟嘌呤核苷酸结合蛋白，它在体外与视紫红质、毒蕈碱及其他受体相互作用，并参与离子通道的调节。尽管已报道的Goα亚基的cDNA序列几乎完全相同，但在所有检测物种的组织中都鉴定出了多种分子量形式的mRNA。为了研究Goα mRNA大小异质性的分子基础，从同一个视网膜λgt10 cDNA文库中分离出四个cDNA克隆，该文库先前用于分离λGO9，一个包含Goα完整编码区的克隆。这些克隆根据编码区与λGO9的核苷酸序列同一性被鉴定为Goα克隆；然而，它们在终止密码子后28个核苷酸的3'-非翻译区与λGO9不同。与λGO9 3'-非翻译区中与新分离克隆不同的部分互补的寡核苷酸探针，与牛脑和视网膜中存在的3.0-kb和4.0-kb mRNA杂交，而针对新克隆独特区域的类似探针，与两种组织中的4.0-kb mRNA以及主要在视网膜中发现的2.0-kb mRNA杂交。当来自其他物种的脑多聚腺苷酸RNA与不同的3'-非翻译区探针杂交时也观察到类似的杂交模式。似乎3'-非翻译区的差异可能部分是观察到的Goα mRNA异质性的基础。
