FIG. 4.

ctk1Δ relieves glucose repression of a SUC2-HIS3 reporter. The trp1Δ his3Δ strains FY250 (WT), MCY3663 (ctk1Δ), and MCY3655 (srb11Δ) were transformed with the CEN-TRP1 plasmid pYSH (57). Serial sixfold dilutions of cell suspensions (diluted in 10 mM Tris-HCl [pH 7.0] containing 10 mM EDTA to disperse flocculated cells) were spotted on SC-Trp or SC-Trp-His containing 2% glucose or sucrose, as indicated. The plates were photographed after 4 days at 30°C. For either mutant, the number of colonies on glucose-His was approximately equal to that in the corresponding dilution on sucrose-His, suggesting that possible cross-feeding and stochastic effects did not occur.