FIGURE 2.

NPR1 overexpression increased plasma membrane stability of the Mup1 permease in the hal4 hal5 mutant. The BY4741 hal4 hal5 mutant was transformed with the centromeric plasmid containing a Mup1-GFP fusion and an empty plasmid or an NPR1-containing multicopy plasmid. The indicated strains were grown to mid-log phase in SD medium supplemented with 0.1 m KCl and then transferred to low potassium medium for 2 h (−KCl) or medium supplemented with 0.1 m KCl (+KCl). A, confocal microscopy images of Mup1-GFP localization in the hal4 hal5 mutant under the indicated experimental conditions. B, quantification of the number of cells that show Mup1 exclusively in the plasma membrane (PM), in the plasma membrane, and in the vacuole (PM/VAC) and strictly in the vacuole under the indicated experimental conditions. More than 50 cells were analyzed for each condition in four independent experiments. The bars represent the average value for the independent experiments, the circles represent each individual data point, and the error bars show the S.D. C, immunodetection of Mup1 present in the insoluble fraction isolated from the indicated strains. Asterisks (*) indicate statistical significance (t test) with a p value < 0.05. Double asterisks (**) indicate statistical significance with p value < 0.01.