Enriquez-Harris P, Levitt N, Briggs D, Proudfoot N J
Sir William Dunn School of Pathology, University of Oxford, UK.
EMBO J. 1991 Jul;10(7):1833-42. doi: 10.1002/j.1460-2075.1991.tb07709.x.
Termination of transcription by RNA polymerase II has been postulated to involve a pausing process. We have identified such a pause signal, 350 bp into the 3' flanking region of the human alpha 2 globin gene at a position where termination is thought to occur. We show that this pause signal enhances the utilization of an upstream poly(A) site which is otherwise out-competed by a stronger downstream poly(A) site. We also demonstrate that the pause site rescues a poly(A) site that is inactive due to its location within an intron. Using nuclear run-on analysis we show that elongating RNA polymerase II molecules accumulate over this pause signal. Furthermore we show that when the pause site is positioned immediately downstream of a strong poly(A) signal, significant levels of transcription termination take place.
RNA聚合酶II介导的转录终止被推测涉及一个暂停过程。我们已经在人α2珠蛋白基因3'侧翼区域内350 bp处鉴定出这样一个暂停信号，该位置被认为是终止发生的位点。我们发现这个暂停信号增强了上游多聚腺苷酸化位点的使用效率，否则该上游位点会被更强的下游多聚腺苷酸化位点竞争。我们还证明，该暂停位点挽救了一个因位于内含子内而无活性的多聚腺苷酸化位点。通过核转录分析，我们发现正在延伸的RNA聚合酶II分子在这个暂停信号上积累。此外，我们还表明，当暂停位点位于强多聚腺苷酸化信号的紧邻下游时，会发生显著水平的转录终止。
