MOLECULAR-CLONING AND EXPRESSION OF THE 32-KDA SUBUNIT OF HUMAN TFIID REVEALS INTERACTIONS WITH VP16 AND TFIIB THAT MEDIATE TRANSCRIPTIONAL ACTIVATION

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 hTAF(II)32, We find that hTAF(II)32 is the human homologue of Drosophila TAF(II)40. In vitro protein-protein interaction assays reveal that as observed with Drosophila TAF(II)40, hTAF(II)32 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 hTAF(II)32 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.