TBP-associated factors (TAF II s): multiple, selective transcriptional mediators in common complexes

Abstract

Transcription of eukaryotic structural genes requires the assembly of RNA polymerase II and the general transcription factors (GTFs) on the promoter to form a pre-initiation complex (PIC). Among these, TFIID is the major sequence-specific DNA-binding component; the other GTFs enter the PIC primarily through protein–protein interactions. TFIID is composed of the TATA-box-binding protein (TBP) and multiple TBP-associated factors (TAF _IIs). Unexpectedly, TAF _IIs have also been found in other multi-subunit complexes involved in transcription. Whereas TBP is a general transcription factor, a variety of in vivo studies have demonstrated that TAF _IIs are highly promoter selective. Here I review studies on the role of TAF _IIs in genome-wide transcription and their mechanism of action.