FIG. 3.

l-Malic acid efflux from S. cerevisiae strains. S. cerevisiae V5 YEp cells were preloaded by 2 h of incubation with 2 mM labeled l-malic acid (specific activity, 2 × 10⁵ dpm/μmol). The control experiment was performed by diluting 200 μl of cell suspension containing 12 mM labeled l-malic acid with 2 ml of 0.1 M K₂PO₄ buffer, pH 6 (line A). S. cerevisiae V5 YEp MAE1 cells were preloaded with 14.45 mM (▴) or 9.4 mM (●, ■) labeled l-malic acid by incubation with 2 or 10 mM labeled l-malic acid, respectively (specific activity; 10 × 10⁵ and 2 × 10⁵ dpm/μmol), and 200 μl of preloaded cell suspension was diluted with 2 ml of 0.1 M potassium phosphate buffer, pH 4 (line B), pH 3.5 (line C), or pH 6 (line D).