Multiple transcription start sites, DNase I-hypersensitive sites, and an opposite-strand exon in the 5' region of the CHO dhfr gene.
Multiple transcription start sites, DNase I-hypersensitive sites, and an opposite-strand exon in the 5' region of the CHO dhfr gene.
复制标题
CHO dhfr 基因 5 区域有多个转录起始位点、DNase I 超敏位点和一个相反链外显子。
DOI：
10.1128/mcb.6.2.425-440.1986
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发表时间：
1986
影响因子：
5.3
通讯作者：
Chasin,LA
中科院分区：
文献类型：
--
作者：
Mitchell,PJ;Carothers,AM;Han,JH;Harding,JD;Kas,E;Venolia,L;Chasin,LA
Transcription of the 26-kilobase (kb) dihydrofolate reductase (dhfr) gene in CHO cells is initiated at two sites: a major site (approximately 85% of thedhfrmRNA) at -63 relative to the translation start and a minor site (approximately 15%) at -107. Transcription also occurs from the opposite DNA strand in thedhfr5′ region, with a probable initiation site at approximately -195 relative to thedhfrtranslation start. A 4-kb polyadenylated RNA that is derived from the opposite-strand transcription increases threefold in abundance after serum starvation of CHO cells for 24 h.dhfrmRNA levels do not change during this time. The firstdhfrexon lies within a 1-kb genomic region marked by exceptionally high G + C content and lack of DNA methylation. This region also includes a 214-base-pair (bp) exon for the opposite-strand transcript and five of the six DNase I-hypersensitive sites identified at thedhfrlocus. Analysis of the DNA sequences of hamster, human (M. Chen, T. Shimada, A. D. Moulton, A. Cline, R. K. Humphries, J. Maizel, and A. W. Nienhuis, J. Biol. Chem. 259:3933-3943, 1984), and mouse (M. McGrogan, C. C. Simonsen, D. T. Smouse, P. J. Farnham, and R. T. Schimke, J. Biol. Chem. 260:2307-2314, 1985)dhfrgenes reveals the presence of a 29-bp unit that is conserved 45 to 49 bp upstream of major and minordhfrtranscription start sites. This unit follows the consensus: GRGGCGGTGGCCTNNNNTGTCRCAARTRGGTR. The 5′ part of the 29-bp unit contains a GC box that agrees with the GGGCGG consensus-binding site for the RNA polymerase II transcription factor Sp1 (D. Gidoni, W. A. Dynan, and R. Tjian, Nature (London) 312:409-413, 1984). Each of the three mammaliandhfrgenes has several G-rich GC boxes proximal to the majordhfrtranscription start site and several GC boxes of the opposite orientation (C rich) in a distal region about 500 bp upstream.
