Conaway J W, Bradsher J N, Tan S, Conaway R C
Program in Molecular and Cell Biology, Oklahoma Medical Research Foundation, Oklahoma City 73104.
Cell Mol Biol Res. 1993;39(4):323-9.
A growing body of evidence suggests that the elongation stage of eukaryotic messenger RNA synthesis is a major site for the regulation of gene expression. In the process of investigating the mechanism of promoter-specific transcription by RNA polymerase II, we recently identified and purified a novel transcription factor that controls RNA chain elongation. This factor, which we have designated SIII, has a native molecular mass of 140 kDa and is composed of three polypeptides of 110, 18, and 15 kDa. Results of renaturation experiments indicate that all three polypeptides are required to reconstitute SIII transcriptional activity. A variety of evidence from mechanistic studies reveals that SIII dramatically stimulates the rate of RNA chain elongation by RNA polymerase II, most likely through a direct interaction with transcribing polymerase. Here we describe the properties of SIII as well as its role in regulating the activity of the RNA polymerase II elongation complex.
越来越多的证据表明，真核生物信使核糖核酸（mRNA）合成的延伸阶段是基因表达调控的主要位点。在研究RNA聚合酶II进行启动子特异性转录的机制过程中，我们最近鉴定并纯化了一种控制RNA链延伸的新型转录因子。我们将该因子命名为SIII，其天然分子量为140 kDa，由分子量分别为110 kDa、18 kDa和15 kDa的三种多肽组成。复性实验结果表明，重建SIII转录活性需要所有这三种多肽。来自机理研究的各种证据显示，SIII很可能通过与正在转录的聚合酶直接相互作用，极大地刺激了RNA聚合酶II的RNA链延伸速率。在此，我们描述了SIII的特性及其在调节RNA聚合酶II延伸复合物活性中的作用。
