转录终止因子La也是RNA聚合酶III的起始因子。
Transcription termination factor La is also an initiation factor for RNA polymerase III.
作者信息
Maraia R J
机构信息
Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-2753, USA.
出版信息
Proc Natl Acad Sci U S A. 1996 Apr 16;93(8):3383-7. doi: 10.1073/pnas.93.8.3383.
La RNA-binding protein is a transcription termination factor that facilitates recycling of template and RNA polymerase (pol) 111. Transcription complexes preassembled on immobilized templates were depleted of pol III after a single round of RNA synthesis in the presence of heparin and sarkosyl. The isolated complexes could then be complemented with highly purified pol III and/or recombinant La to test if La is required for transcription reinitiation. VA1, 7SL, and B1 transcription complexes cannot be transcribed by supplemental pol III in single or multiple-round transcription assays unless La is also provided. La mediates concentration-dependent activation of pol III initiation and thereby controls the use of preassembled stable transcription complexes. The initiation factor activity of La augments its termination factor activity to produce a novel mechanism of activated reinitiation. A model in which La serves pol III upon transcription initiation and again at termination is discussed.
La RNA结合蛋白是一种转录终止因子，可促进模板和RNA聚合酶（pol）III的循环利用。在肝素和 Sarkosyl存在的情况下，经过一轮RNA合成后，固定模板上预组装的转录复合物中的pol III被耗尽。然后，可以用高度纯化的pol III和/或重组La补充分离的复合物，以测试La是否是转录重新起始所必需的。在单轮或多轮转录试验中，除非同时提供La，否则VA1、7SL和B1转录复合物不能被补充的pol III转录。La介导pol III起始的浓度依赖性激活，从而控制预组装稳定转录复合物的使用。La的起始因子活性增强了其终止因子活性，从而产生了一种激活重新起始的新机制。本文讨论了一种模型，即La在转录起始时和终止时都为pol III服务。
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