Klemm R D, Goodrich J A, Zhou S, Tjian R
Howard Hughes Medical Institute, Department of Molecular and Cell Biology, University of California, Berkeley 94720-3202, USA.
Proc Natl Acad Sci U S A. 1995 Jun 20;92(13):5788-92. doi: 10.1073/pnas.92.13.5788.
Transcription factor TFIID consists of TATA binding protein (TBP) and at least eight TBP-associated factors (TAFs). As TAFs are required for activated but not basal transcription, we have proposed that TAFs act as coactivators to mediate signals between activators and the basal transcription machinery. Here we report the cloning, expression, and biochemical characterization of the 32-kDa subunit of human (h) TFIID, termed hTAFII32. We find that hTAFII32 is the human homologue of Drosophila TAFII40. In vitro protein-protein interaction assays reveal that as observed with Drosophila TAFII40, hTAFII32 interacts with the C-terminal 39-amino acid activation domain of the acidic transactivator viral protein 16 (VP16) as well as with the general transcription factor TFIIB. Moreover, a partial recombinant TFIID complex containing hTAFII32 was capable of mediating in vitro transcriptional activation by the VP16 activation domain. These findings indicate that specific activator-coactivator interactions have been conserved between human and Drosophila and provide additional support for the function of these interactions in mediating transcriptional activation.
转录因子TFIID由TATA结合蛋白（TBP）和至少8种TBP相关因子（TAF）组成。由于TAF是激活转录而非基础转录所必需的，我们提出TAF作为辅激活因子，在激活因子和基础转录机制之间介导信号传递。在此，我们报道了人（h）TFIID的32 kDa亚基（称为hTAFII32）的克隆、表达及生化特性。我们发现hTAFII32是果蝇TAFII40的人类同源物。体外蛋白质-蛋白质相互作用分析表明，与果蝇TAFII40一样，hTAFII32与酸性反式激活因子病毒蛋白16（VP16）的C末端39个氨基酸的激活结构域以及通用转录因子TFIIB相互作用。此外，含有hTAFII32的部分重组TFIID复合物能够介导VP16激活结构域的体外转录激活。这些发现表明，人和果蝇之间特定的激活因子-辅激活因子相互作用是保守的，并为这些相互作用在介导转录激活中的功能提供了额外支持。
