Ruppert S, Wang E H, Tjian R
Howard Hughes Medical Institute, Department of Molecular and Cell Biology, University of California, Berkeley 94720.
Nature. 1993 Mar 11;362(6416):175-9. doi: 10.1038/362175a0.
Basal transcription by human RNA polymerase II requires the coordinate action of several ancillary factors (TFIIA-J) and can be regulated by various promoter-specific DNA binding proteins. An additional class of factors, called coactivators, are dispensable for basal transcription but are indispensable for regulation by transcriptional activators. Biochemical studies established that some coactivators are associated with the TATA-binding protein (TBP) to form the TFIID complex. We therefore set out to define the relationship between TBP and these TBP-associated factors (TAFs). Here we describe the cloning, expression and properties of the first human TAF, hTAFII250. The hTAFII250 gene is identical to a gene, CCG1, (ref 7,8), implicated in cell-cycle progression. Recombinant hTAFII250 binds directly to TBP both in vitro and in yeast, and participates in the formation of the TFIID complex. This largest TAF may therefore play a central role in TFIID assembly by interacting with both TBP and other TAFs, as well as serving to link the control of transcription to the cell cycle.
人类RNA聚合酶II的基础转录需要几种辅助因子（TFIIA - J）的协同作用，并且可以由各种启动子特异性DNA结合蛋白进行调控。另一类因子，称为共激活因子，对于基础转录是可有可无的，但对于转录激活因子的调控却是必不可少的。生化研究表明，一些共激活因子与TATA结合蛋白（TBP）相关联，形成TFIID复合物。因此，我们着手确定TBP与这些TBP相关因子（TAFs）之间的关系。在此，我们描述了首个人类TAF，即hTAFII250的克隆、表达及其特性。hTAFII250基因与一个名为CCG1的基因（参考文献7,8）相同，该基因与细胞周期进程有关。重组hTAFII250在体外和酵母中都能直接与TBP结合，并参与TFIID复合物的形成。因此，这个最大的TAF可能通过与TBP和其他TAFs相互作用，在TFIID组装中发挥核心作用，同时还能将转录控制与细胞周期联系起来。
