| Contrary to expectations , we find that TAF 4 rather than TBP or TAF 1 plays the most critical role in maintaining stability of the complex . ^^^ Based on our results , we propose that holo TFIID comprises a stable core subcomplex containing TAF 4 , TAF 5 , TAF 6 , TAF 9 , and TAF 12 decorated with peripheral subunits TAF 1 , TAF 2 , TAF 11 , and TBP . ^^^ Our initial functional studies indicate a specific and significant role for TAF 1 and TAF 4 in mediating transcription from a TATA less , downstream core promoter element ( DPE ) containing promoter , whereas a TATA containing , DPE less promoter was far less dependent on these subunits . ^^^ In contrast to both TAF 1 and TAF 4 , RNAi knockdown of TAF 5 had little effect on transcription from either class of promoter . ^^^ |