Pugh B F, Tjian R
Howard Hughes Medical Institute, Department of Molecular and Cell Biology, University of California, Berkeley 94720.
Cell. 1990 Jun 29;61(7):1187-97. doi: 10.1016/0092-8674(90)90683-6.
In reconstituted reactions, Sp1 stimulates transcription at TATA-containing promoters in the presence of semipurified TFIID fractions from either human or Drosophila cells, but is unable to do so when these fractions are replaced by purified, cloned Drosophila or yeast TFIID. Our findings with Sp1 and CTF suggest that partially purified TFIID fractions from human and Drosophila cells contain coactivators that are dispensable for basal transcription but are required as molecular adaptors between trans-activators and the general transcription initiation machinery. Experiments using cloned TFIID proteins suggest that these coactivators function through the amino-terminal portion of TFIID and that coactivator-TFIID interactions are species specific. At promoters lacking a TATA box, an additional activity distinct from coactivators is required for Sp1 activation of transcription.
在重组反应中，Sp1在存在来自人类或果蝇细胞的半纯化TFIID组分的情况下，能刺激含TATA框的启动子的转录，但当这些组分被纯化的、克隆的果蝇或酵母TFIID取代时则无法做到。我们关于Sp1和CTF的研究结果表明，来自人类和果蝇细胞的部分纯化的TFIID组分含有共激活因子，这些共激活因子对于基础转录并非必需，但作为反式激活因子与通用转录起始机制之间的分子衔接物是必需的。使用克隆的TFIID蛋白进行的实验表明，这些共激活因子通过TFIID的氨基末端部分发挥作用，并且共激活因子与TFIID的相互作用具有物种特异性。在缺乏TATA框的启动子处，Sp1激活转录需要一种不同于共激活因子的额外活性。
