Figure 2.

Vacuolar V-ATPase determines directionality of Vcx1 operation. (A) Ca²⁺ tolerance assays were performed in duplicate in YPDS medium (black bars) or in the same medium containing 0.2 µg/ml FK506 (gray bars) as described in Materials and Methods, and the derived IC50 values (±SD) for the indicated mutants were plotted on a log scale. (B) The indicated strains were transformed with plasmid pKC190 that bears the PMC1-lacZ reporter gene (Cunningham and Fink 1996) and β-galactosidase activity was measured 4 hr after log-phase cells were shifted to YPDS medium containing 100 mM CaCl₂. Results from three independent transformants were averaged (±SD). * P < 0.05, ** P < 0.01.