Conaway J W, Conaway R C
Department of Chemistry and Clayton Foundation Biochemical Institute, University of Texas, Austin 78712-1096.
J Biol Chem. 1989 Feb 5;264(4):2357-62.
We have fractionated rat liver and identified a set of transcription factors that are essential for accurate initiation of transcription by RNA polymerase II. These factors were resolved into three distinct enzyme fractions. The factors in two of these fractions have been purified to apparent homogeneity. One fraction contains a single, 35-kDa transcription factor, designated alpha (Conaway, J. W., Bond, M. W., and Conaway, R. C. (1987) J. Biol. Chem. 262, 8293-8297). Here we show that the other fraction contains a transcription factor, designated beta gamma, with a native molecular mass of approximately 250 kDa. This factor is composed of 67 kDa (beta) and 31 kDa (gamma) polypeptides. Both the beta and gamma polypeptides are required for runoff transcription. Comparison of purified transcription factors alpha and beta gamma reveals that (i) both factors act at initiation and (ii) neither alpha nor beta gamma is required for assembly of an initial complex that commits the template to be transcribed by RNA polymerase II.
我们对大鼠肝脏进行了分级分离，并鉴定出一组对RNA聚合酶II准确起始转录至关重要的转录因子。这些因子被分离成三个不同的酶级分。其中两个级分中的因子已被纯化至表观均一。一个级分含有一种单一的35 kDa转录因子，命名为α（康纳韦，J.W.，邦德，M.W.，和康纳韦，R.C.（1987年）《生物化学杂志》262，8293 - 8297）。在此我们表明，另一个级分含有一种转录因子，命名为βγ，其天然分子量约为250 kDa。该因子由67 kDa（β）和31 kDa（γ）多肽组成。β和γ多肽对于连续转录都是必需的。纯化的转录因子α和βγ的比较表明：（i）这两种因子都在起始阶段起作用；（ii）对于使模板被RNA聚合酶II转录的起始复合物的组装，α和βγ都不是必需的。
