FIG. 1.

Alternative dependence of CIT1 expression on RTG1, RTG2, RTG3, and HAP2. β-Galactosidase assays were carried out to determine the activity of a CIT1-lacZ reporter gene in wild-type (WT) PSY142 [rho⁺] and [rho⁰] cells and various mutant derivatives of these strains as indicated. The bp −806 to +9 region of the CIT1 gene was fused to the coding region of the E. coli lacZ gene, and the resulting construct was integrated at the chromosomal CIT1 locus. For each strain grown on either raffinose (YPR) or glucose (YP5%D) medium, four independent transformants were pooled from mid-log-phase cultures and β-galactosidase assays on whole-cell extracts were carried out in triplicate as described in Materials and Methods.