Water Transport across Yeast Vacuolar and Plasma Membrane-Targeted Secretory Vesicles Occurs by Passive Diffusion |
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| Authors: | Larry A. Coury Mark Hiller John C. Mathai Elizabeth W. Jones Mark L. Zeidel Jeffrey L. Brodsky |
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| Affiliation: | Laboratory of Epithelial Cell Biology, Renal Electrolyte Division, Department of Medicine, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania 15213-2500, USA. |
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| Abstract: | To determine whether solute transport across yeast membranes was facilitated, we measured the water and solute permeations of vacuole-derived and late secretory vesicles in Saccharomyces cerevisiae; all permeations were consistent with passive diffusive flow. We also overexpressed Fps1p, the putative glycerol facilitator in S. cerevisiae, in secretory vesicles but observed no effect on water, glycerol, formamide, or urea permeations. However, spheroplasts prepared from the strain overexpressing Fps1p showed enhanced glycerol uptake, suggesting that Fps1p becomes active only upon insertion in the plasma membrane. |
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