The general transcription factor TFIID is composed of the TATA-box- binding protein (TBP) and a set of TBP-associated factors (TAF(II)s) (ref. 1). In vitro, TAF(II)s are required for activated transcription, and have been proposed to be obligatory targets of transcriptional activator proteins (activators). The function of TAF(II)s has not been investigated systematically in vivo. A Saccharomyces cerevisiae TAF(II) complex (yTAF(II) complex) has been identified that shares functional and structural similarities with higher eukaryotic TFIID. In particular, most yTAF(II)s are the homologue of a higher eukaryotic TAF(II) (refs 3, 4). Here we report that inactivation or depletion of six different yTAF(II)s, including the core yTAF(II) that contacts TBP, does not compromise transcriptional activation. We conclude that in vivo, activated transcription of many genes can occur in the absence of functional yTAF(II)s, and that in these instances another transcription component(s) must be the target of the activator.
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