期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1980
卷号：77
期号：3
页码：1417-1421
DOI：10.1073/pnas.77.3.1417
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The transcription and processing of mitochondrial 21S rRNA in a petite strain of Saccharomyces cerevisiae has been examined by electron microscopic analysis of R-loop hybrids and by hybridization of labeled mitochondrial DNA probes to RNA transferred to diazobenzyloxymethyl paper. We have shown the presence of a large [5.1- to 5.4-kilobase (kb)] transcript that appears to be a precursor of mitochondrial 21S rRNA. This transcript contains sequences homologous to those of the mature 21S rRNA, to the intervening sequence present in the gene, and to additional sequences at the 3' end of the molecule. Our data suggest that this precursor of 21S rRNA is processed in two steps. The intron sequence is usually excised first, followed by removal of the extra 3' sequences. In some cases, however, the 3' extension is first removed and the intron sequence is then excised. Both pathways appear to lead to formation of the 3.1-kb mature 21S rRNA and a stable 1.2-kb intron transcript. Similar results were obtained with grande MH41-7B mitochondrial RNA by RNA transfer hybridization. We have also observed a number of additional transcripts that may be normal processing intermediates or may result from faulty cleavage-ligation during excision of the intervening sequence.
