Figure 1.

Recruitment of TFIID to a target promoter by fusing TAF90 or TAF60 to the transcriptionally inactive DNA-binding protein RFX stimulates transcription. The activity of a lacZ reporter gene bearing a single RFX-binding site (X) upstream of the his3 TATA element (14) was assessed in yeast strains expressing the indicated proteins from plasmid DNAs. The proteins were either expressed at low levels from the TBP promoter on a centromeric plasmid, or overproduced by introducing the genes into the multicopy vector pYES2 (Invitrogen) under control of the GAL1 promoter. Transformed yeast cells were grown in selective medium containing galactose and assayed for β-galactosidase activity. In this and the other figures of this paper, values are relative to the level of β-galactosidase activity seen with VP16–RFX under normal conditions: this amount was assigned a value of 100. Tx refers to the remainder of the general factors and pol II.