Dubin D T, Timko K D, Baer R J
Cell. 1981 Jan;23(1):271-8. doi: 10.1016/0092-8674(81)90291-9.
The 3'-terminal sequence of the large ribosomal subunit ("17S") RNA of hamster mitochondria has been examined by means of oligonucleotide fingerprint analysis of 3' end-labeled samples. Patterns from partial acid or alkaline hydrolysates indicated marked heterogeneity and suggested an array of termini that included GGUUAOH, AnAOH and AnGOH (where n is about 10). Patterns from samples subjected to exhaustive digestion with ribonucleases T1 plus A, or with each separately, confirmed these inferences, and strikingly demonstrated the existence of oligoadenylated families of 3'-terminal sequences. Under the assumption that the oligoadenylate was added posttranscriptionally, these results indicated that the 3'-terminal transcribed moieties consist of variants of YAGGUUOH. Counting from the last U, we inferred that many such sequences end at U1 and G4, while smaller numbers end at G3 and A5; and that major sites of oligoadenylation occur at U1 and G4, and a minor site occurs at A5. This novel combination of imprecise termination of transcription or "sizing" of transcripts, and variable addition of adenylate residues, is discussed with regard to the mechanism of expression of the mammalian mitochondrial ribosomal RNA genes.
通过对3'末端标记样品进行寡核苷酸指纹分析，研究了仓鼠线粒体大核糖体亚基（“17S”）RNA的3'末端序列。部分酸或碱水解产物的图谱显示出明显的异质性，并提示存在一系列末端，包括GGUUAOH、AnAOH和AnGOH（其中n约为10）。用核糖核酸酶T1加A或分别用每种酶进行彻底消化的样品的图谱证实了这些推断，并显著证明了3'末端序列的寡聚腺苷酸化家族的存在。假设寡聚腺苷酸是转录后添加的，这些结果表明3'末端转录部分由YAGGUUOH的变体组成。从最后一个U开始计数，我们推断许多这样的序列在U1和G4处结束，而较少数量的序列在G3和A5处结束；并且寡聚腺苷酸化的主要位点发生在U1和G4，次要位点发生在A5。关于哺乳动物线粒体核糖体RNA基因的表达机制，讨论了这种转录终止不精确或转录本“大小调整”与腺苷酸残基可变添加的新颖组合。
