FIG. 4.

[³H]glycerol uptake (expressed as counts per minute, 10³) was measured at 26°C in yeast spheroplasts containing the FPS1 overexpression plasmid (closed circles) or the same plasmid lacking the FPS1 insert (open circles). An immunoblot analysis was performed as described in the legend to Fig. 3 on each sample to verify that Fps1p was overexpressed (data not shown). Light scattering of the different preparations ensured that equal amounts of spheroplasts were used in these experiments. The background (0 min), obtained by mixing spheroplasts with [³H]glycerol and immediately processing the sample (see text for details), was subtracted from each data set.