YEAST TAF(II)S IN A MULTISUBUNIT COMPLEX REQUIRED FOR ACTIVATED TRANSCRIPTION

IN higher eukaryotes the RNA polymerase II transcription factor TFIID is composed of a TATA-box-binding protein (TBP) and a set of tightly b ound polypeptides, designated TBP-associated fao tors (TAF(II)s). One or more TAF(II)s are coactivators that are required for activated but not basal transcription(1-3). The eukaryotic transcription machinery i s highly conserved and it is therefore puzzling that TAF(II)s have aot been identified in yeast. Here we use TBP as a protein-affinity ligan d to isolate from yeast a multi-subunit complex that is required speci fically for activated transcription by RNA polymerase II. Microsequenc e analysis and cloning of two subunits of this complex reveal that the y are the homologues of known mammalian and Drosophila TAF(II)s. The g enes encoding these two yeast TAF(II)s are essential, suggesting that activated transcription is required for viability of Saccharomyces cer evisiae.