Ingles C J, Himmelfarb H J, Shales M, Greenleaf A L, Friesen J D
Proc Natl Acad Sci U S A. 1984 Apr;81(7):2157-61. doi: 10.1073/pnas.81.7.2157.
Three different regions of Saccharomyces cerevisiae DNA were identified by using as hybridization probe a fragment of Drosophila melanogaster DNA that encodes an RNA polymerase II (EC 2.7.7.6) polypeptide. Two of these regions have been molecularly cloned. Each contains a sequence related not only to the D. melanogaster DNA fragment that was used as a probe in its isolation but also to the immediately adjacent DNA fragment of the D. melanogaster RNA polymerase II gene. The two cloned S. cerevisiae DNA sequences are each the template for single transcripts in vivo, one of 5.9 kilobases and the other of 4.6 kilobases. In vitro translation of hybrid-selected cellular RNA indicated that the former locus encodes a protein of Mr 220,000, equal in size to the largest polypeptide subunit of S. cerevisiae RNA polymerase II. Disruption of either gene by targeted integration of URA3+ DNA demonstrated that each is single-copy and essential in a haploid genome. We suggest that these S. cerevisiae loci are members of a family of related genes encoding the largest subunit polypeptides of RNA polymerases I, II, and III.
通过使用果蝇（Drosophila melanogaster）DNA的一个片段作为杂交探针，该片段编码一种RNA聚合酶II（EC 2.7.7.6）多肽，鉴定出了酿酒酵母（Saccharomyces cerevisiae）DNA的三个不同区域。其中两个区域已被分子克隆。每个区域都包含一个不仅与在其分离过程中用作探针的果蝇DNA片段相关，而且与果蝇RNA聚合酶II基因紧邻的DNA片段相关的序列。两个克隆的酿酒酵母DNA序列在体内均为单转录本的模板，一个为5.9千碱基，另一个为4.6千碱基。对杂交选择的细胞RNA进行体外翻译表明，前一个基因座编码一个分子量为220,000的蛋白质，其大小与酿酒酵母RNA聚合酶II的最大多肽亚基相同。通过URA3 + DNA的靶向整合破坏任何一个基因，表明每个基因在单倍体基因组中都是单拷贝且必不可少的。我们认为这些酿酒酵母基因座是编码RNA聚合酶I、II和III最大亚基多肽的相关基因家族的成员。
