FIG. 2.
Reversibility of Mae1p-mediated l-malate transport in S. cerevisiae. Experiments were performed in 0.1 M K2PO4 buffer, pH 3.5, with an initial extracellular total l-malic acid concentration of 2 mM (specific activity, 3 × 105 dpm/μmol). Line A, accumulation of l-malic acid by the S. cerevisiae strain V5 YEp MAE1 without addition; lines B and C, addition (arrow) of unlabeled l-malic acid or 14C-labeled l-malic acid (specific activity, 3 × 105 dpm/μmol), respectively, to the accumulation assay with the recombinant S. cerevisiae strain at a final concentration of 35 mM. The ratio between the intracellular concentrations of labeled l-malic acid (line B) and total l-malic acid (line C) was calculated (line D).