FIG. 7.

Base substitutions in the vicinity of transcription start sites can alter their sensitivity to TFIIB mutations. (A) Presented is the DNA sequence of the transcription initiation regions in the ADH1 and HIS3 promoters. Underlined in bold is the CAPuGC motif present at both of the ADH1 start sites and at the HIS3 −23 start site. (B) Primer extension analyses were performed as described in the legend to Fig. 6 using yeast strains containing the ADH1 or T(−40)C mutant ADH1 promoter constructs and either wild-type TFIIB or the indicated TFIIB mutant. (C) Primer extension analyses were performed using yeast strains containing the ADH1-HIS3 or G(−25)T mutant ADH1-HIS3 promoter constructs and either wild-type TFIIB or the indicated TFIIB mutant.