Sierra F, Pittet A C, Schibler U
Mol Cell Biol. 1986 Nov;6(11):4067-76. doi: 10.1128/mcb.6.11.4067-4076.1986.
We cloned the rat alpha-amylase gene Amy-1 and compared its structure and expression with its mouse counterpart. The results showed that the general organization of the transcriptionally active rat Amy-1 gene was similar to that of its mouse counterpart; i.e., the rat gene also contained two independent transcriptional promoters. The distance between the two promoters in the rat gene was, however, more than double (6 kilobases) that measured in the mouse gene (2.8 kilobases). In addition, the rat genome also contained an independent, orphonlike version of the weaker Amy-1 promoter, which was transcriptionally silent. In spite of the similar overall organization of the Amy-1 genes in mouse and rat cells, an interesting difference was observed in the expression of the weak promoter in these two closely related rodents. In rats this promoter was significantly active only in liver cells, while in mice it was utilized with similar efficiencies in parotid, liver, and pancrease cells. Moreover, the transcripts produced in rat liver had a very heterogeneous population of 5' ends, located between 180 and 220 nucleotides upstream of the two homologous start sites observed for this promoter in mouse liver, even though the sequences around this region were strongly conserved between the two species.
我们克隆了大鼠α-淀粉酶基因Amy-1，并将其结构和表达与其小鼠对应物进行了比较。结果表明，转录活性的大鼠Amy-1基因的总体组织与其小鼠对应物相似；即大鼠基因也包含两个独立的转录启动子。然而，大鼠基因中两个启动子之间的距离是小鼠基因（2.8千碱基）中测量距离的两倍多（6千碱基）。此外，大鼠基因组还包含一个较弱的Amy-1启动子的独立的、类孤儿版本，它在转录上是沉默的。尽管小鼠和大鼠细胞中Amy-1基因的总体组织相似，但在这两种密切相关的啮齿动物中，弱启动子的表达存在有趣的差异。在大鼠中，这个启动子仅在肝细胞中显著活跃，而在小鼠中，它在腮腺、肝脏和胰腺细胞中的利用效率相似。此外，大鼠肝脏中产生的转录本具有非常异质的5'末端群体，位于在小鼠肝脏中观察到的该启动子的两个同源起始位点上游180至220个核苷酸之间，尽管这两个物种在该区域周围的序列高度保守。
