Drees B, Ali Z, Soeller W C, Coleman K G, Poole S J, Kornberg T
Department of Biochemistry and Biophysics, University of California, San Francisco 94143.
EMBO J. 1987 Sep;6(9):2803-9. doi: 10.1002/j.1460-2075.1987.tb02576.x.
Transcripts from the engrailed gene of Drosophila melanogaster have been characterized by Northern, S1 nuclease sensitivity, and primer extension analyses. The engrailed gene encodes three poly(A)+ transcripts (3.6 kb, 2.7 kb, and 1.4 kb) that derive from a 3.9-kb portion of the genome. No other transcribed regions were found up to 16 kb downstream and 48 kb upstream of the engrailed transcription unit, the portion of the genome to which engrailed mutations have been mapped. The structures of the engrailed transcripts are unaffected by lethal engrailed mutations that break the locus at points in the transcriptionally silent regions. Transcripts expressed by 145 kb of DNA that surround the engrailed locus were also identified by Northern analysis. In contrast to the large portion of the engrailed gene that is transcriptionally inactive, most of the surrounding regions are 10-fold more densely populated with transcripts. We presume that the unusually large silent region at the periphery of the engrailed transcription unit signify the presence of special mechanisms that regulate its expression.
黑腹果蝇的engrailed基因转录本已通过Northern印迹、S1核酸酶敏感性和引物延伸分析进行了表征。engrailed基因编码三种聚腺苷酸化（poly(A)+）转录本（3.6 kb、2.7 kb和1.4 kb），它们源自基因组的一个3.9 kb区域。在engrailed转录单元（engrailed突变已定位到的基因组部分）下游16 kb和上游48 kb范围内未发现其他转录区域。engrailed转录本的结构不受致死性engrailed突变的影响，这些突变在转录沉默区域的位点处破坏了该基因座。通过Northern分析还鉴定了围绕engrailed基因座的145 kb DNA所表达的转录本。与engrailed基因大部分转录无活性形成对比的是，其周围大部分区域的转录本密度要高10倍。我们推测，engrailed转录单元周边异常大的沉默区域表明存在调节其表达的特殊机制。
