Thompson C M, Young R A
Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA.
Proc Natl Acad Sci U S A. 1995 May 9;92(10):4587-90. doi: 10.1073/pnas.92.10.4587.
Yeast RNA polymerase II holoenzymes have been described that consist of RNA polymerase II, a subset of general transcription factors, and nine SRB regulatory proteins. The feature that distinguishes the RNA polymerase II holoenzymes from other forms of RNA polymerase II in the cell is their tight association with SRB proteins. We investigated the fraction of genes that require SRB proteins in vivo by examining the effect of temperature-sensitive mutations in SRB genes on transcription by RNA polymerase II. Upon transfer to the restrictive temperature, there is a rapid and general shutdown of mRNA synthesis in srb mutant cells. These data, combined with the observation that essentially all of the SRB protein in cells is tightly associated with RNA polymerase II molecules, argue that SRB-containing holoenzymes are the form of RNA polymerase II recruited to most promoters in the cell.
酵母RNA聚合酶II全酶已被描述为由RNA聚合酶II、一般转录因子的一个子集以及九种SRB调节蛋白组成。RNA聚合酶II全酶与细胞中其他形式的RNA聚合酶II的区别在于它们与SRB蛋白紧密结合。我们通过研究SRB基因中温度敏感突变对RNA聚合酶II转录的影响，来调查体内需要SRB蛋白的基因比例。转移到限制温度后，srb突变细胞中的mRNA合成迅速且普遍停止。这些数据，再加上观察到细胞中基本上所有的SRB蛋白都与RNA聚合酶II分子紧密结合，表明含SRB的全酶是细胞中被招募到大多数启动子上的RNA聚合酶II的形式。
