Calabi F, Neuberger M S
EMBO J. 1985 Mar;4(3):667-74. doi: 10.1002/j.1460-2075.1985.tb03681.x.
In many mouse plasmacytomas, the active c-myc gene has been truncated by chromosome translocation with the resultant severance of the protein-coding sequence from the normal promoter. Transcripts of such truncated c-myc genes were analyzed by Northern blotting, nuclease S1 mapping, primer extension assays and cDNA cloning. We conclude that transcription originates from multiple initiation sites on both c-myc coding and non-coding strands with the two-sets of transcripts derived from adjacent but essentially non-overlapping regions located greater than 1 kb from the translocation junction. In X63Ag8, where c-myc is translocated to the immunoglobulin C gamma 2b gene, the c-myc non-coding strand transcripts include the translocation junction and then splice directly into the gamma 2b CH1 exon. We propose that chromosome translocation activates a cryptic promoter in the first intron and that the heterogeneously initiated, bipolar transcription reflects the absence of a suitably placed TATA box element.
在许多小鼠浆细胞瘤中，活性c-myc基因已因染色体易位而被截断，导致蛋白质编码序列与正常启动子分离。通过Northern印迹、核酸酶S1图谱分析、引物延伸试验和cDNA克隆对这种截断的c-myc基因转录本进行了分析。我们得出结论，转录起源于c-myc编码链和非编码链上的多个起始位点，两组转录本来自与易位连接点距离大于1 kb的相邻但基本不重叠的区域。在X63Ag8中，c-myc易位至免疫球蛋白Cγ2b基因，c-myc非编码链转录本包含易位连接点，然后直接剪接至γ2b CH1外显子。我们提出，染色体易位激活了第一个内含子中的一个隐蔽启动子，而异源起始的双极转录反映了缺乏合适位置的TATA盒元件。
