一个源自异常加工的RNA分子的小鼠胸苷酸合成酶假基因。

A mouse thymidylate synthase pseudogene derived from an aberrantly processed RNA molecule.

作者信息

Li D W, Johnson L F

机构信息

Department of Biochemistry, Ohio State University, Columbus 43210.

出版信息

Gene. 1989 Oct 30;82(2):363-70. doi: 10.1016/0378-1119(89)90064-4.

DOI:10.1016/0378-1119(89)90064-4

PMID:2573561

Abstract

A DNA fragment containing a mouse-thymidylate-synthase(TS) processed pseudogene was cloned and analyzed. Comparison with the sequences of the mouse TS-encoding gene (ts) and cDNA revealed that the pseudogene started at one of the normal 5' termini of TS mRNA, ended with a poly(A) tail, and was flanked by 16-nucleotide (nt) direct repeats. The region corresponding to the open reading frame was 97.3% identical to that of the cDNA. Two unusual features were observed. First, the poly(A) tail of the pseudogene was located 2 kb downstream from the normal location. Second, the final 10 nt of intron 5 were retained in the 'coding region' of the pseudogene. Therefore, it appears that the pseudogene was derived from a nonfunctional TS 'mRNA' that was aberrantly spliced and polyadenylated. Analysis of the sequence of intron 5 of the ts gene revealed the presence of an alternative 3' splice site 10 nt upstream from the normal splice site. S1-nuclease protection assays showed that about 10% of TS mRNA isolated from mouse cells was spliced at the alternative site.

摘要

克隆并分析了一个包含小鼠胸苷酸合成酶（TS）加工假基因的DNA片段。与小鼠TS编码基因（ts）和cDNA的序列比较表明，该假基因起始于TS mRNA正常的5'末端之一，以聚腺苷酸尾结束，并两侧有16个核苷酸（nt）的直接重复序列。与cDNA开放阅读框对应的区域有97.3%的同源性。观察到两个不寻常的特征。第一，假基因的聚腺苷酸尾位于正常位置下游2 kb处。第二，内含子5的最后10个nt保留在假基因的“编码区”。因此，该假基因似乎来源于一个异常剪接和聚腺苷酸化的无功能TS“mRNA”。对ts基因内含子5序列的分析显示，在正常剪接位点上游10 nt处存在一个可变3'剪接位点。S1核酸酶保护试验表明，从小鼠细胞中分离的TS mRNA约有10%在可变位点处剪接。