Samuelson L C, Wiebauer K, Howard G, Schmid R M, Koeplin D, Meisler M H
Department of Human Genetics, University of Michigan, Ann Arbor 48109-0618.
Nucleic Acids Res. 1991 Dec 25;19(24):6935-41. doi: 10.1093/nar/19.24.6935.
The mouse pancreatic ribonuclease gene Rib-1 was isolated from a library of mouse genomic DNA and sequenced. This small gene contains a nontranslated exon of 52 base pairs, an intron of 791 base pairs, and a coding exon of 741 base pairs. Rib-1 transcripts were detected in parotid gland as well as in pancreas. The abundance of the transcripts were approximately 200-fold greater in pancreatic RNA than in parotid RNA. The sites of transcription initiation were mapped by primer extension and ribonuclease protection assays. One major initiation site and several minor initiation sites were identified in pancreatic RNA. Transcription in parotid appears to be initiated from the same sites. Parotid-specific transcripts were not detected. The data suggest that Rib-1 is transcribed in pancreas and parotid from the same promoter. This is in contrast with the mechanism for production of amylase in pancreas and parotid, which is accomplished by tissue specific expression of different gene copies.
从小鼠基因组DNA文库中分离出小鼠胰腺核糖核酸酶基因Rib-1并进行测序。这个小基因包含一个52个碱基对的非翻译外显子、一个791个碱基对的内含子和一个741个碱基对的编码外显子。在腮腺和胰腺中均检测到Rib-1转录本。胰腺RNA中转录本的丰度比腮腺RNA中的丰度大约高200倍。通过引物延伸和核糖核酸酶保护试验确定了转录起始位点。在胰腺RNA中鉴定出一个主要起始位点和几个次要起始位点。腮腺中的转录似乎也从相同位点起始。未检测到腮腺特异性转录本。数据表明，Rib-1在胰腺和腮腺中由相同的启动子转录。这与胰腺和腮腺中淀粉酶产生的机制相反，淀粉酶的产生是通过不同基因拷贝的组织特异性表达来实现的。
