Phosphate transport properties of MtPT3 and MtPT5 in yeast.
A, comparison of yeast growth rate. Yeast PAM2 cells expressing
MtPT3, MtPT5, or the pWV3 vector control were grown in synthetic dextrose
medium containing 0.22 mm Pi and 25 mm sodium
citrate buffer at pH 4.5. A600 value was monitored as a
measurement of growth. Values shown are the mean ± S.D. for three
independent experiments. B, phosphate uptake rate as a function of
external phosphate concentration. Phosphate uptake rates of yeast PAM2 cells
carrying MtPT3, MtPT5, or the pWV3 vector control were measured at pH 4.0 with
different external phosphate concentrations. Values are the means from two
independent experiments ± S.D., each with duplicate samples.
Lines are derived from nonlinear regression analysis. C,
phosphate uptake rate as a function of external pH value. The phosphate uptake
rate of yeast PAM2 cells expressing MtPT3 (gray bars), MtPT5
(cross-hatched bars), or carrying the pWV3 vector control (open
bars) was determined at the indicated pH values. Values from one of three
independent experiments are shown, mean ± S.D. for three time point
replicates.