FIG 4.

PHO89 expression under conditions of high-pH stress is regulated by Snf1 and Rim101. (A) The indicated strains, transformed with the pPHO89-LacZ reporter, were exposed to pH 8.0 or maintained at pH 5.5, and β-galactosidase activity was determined. Data are means ± standard errors of the means from 10 to 15 experiments. (B) Wild-type DBY476, RSC10 (snf1), and RSC21 (rim101) cells were collected at the indicated times after switching the medium to pH 8.0, and total RNA was prepared. Semiquantitative RT-PCR was performed as described in the legend to Fig. 2A. Signals were integrated, and bars at the bottom of each panel denote the ratios between the PHO89 and ACT1 mRNAs for each time point and strain. (C) The above-mentioned strains plus strain RSC4 (pho4) were subjected to pH 8.0 for the indicated times and processed as described in the legend to Fig. 1A, and the amount of Pho89 was revealed by immunoblotting.