Figure 3. Alkaline pH triggers nuclear entry of the Msn2 transcription factor.

Cultures of wild-type BY4741 (WT) and its ira2::kanMX derivative (right-hand panels) were transformed with plasmid pMsn2-GFP and subjected to pH stress (8.0) on YPD medium. Samples were collected at the specified times and fixed for fluorescence microscopy. (B) BY4741 cells carrying the pMsn2-GFP construct were grown to exponential phase (A₆₆₀ of 0.8) on YPD medium or YP medium containing ethanol (2%) as the carbon source, shifted to pH 8.0. The subcellular distribution of the Msn2–GFP fusion was monitored for at least 200 cells per time point. Open bars denote full cytoplasmic, closed bars denote nuclear/cytoplasmic and crossed bars denote full nuclear localization. The results shown correspond to a representative experiment. Three independent experiments were performed with similar results.