Phosphate transport in yeast vacuoles.
The vacuole of the yeast Saccharomyces cerevisiae is a major storage compartment for phosphate. We have measured phosphate transport across the vacuolar membrane. Isolated intact vacuoles take up large amounts of added [32P]phosphate by counterflow exchange with phosphate present in the vacuoles at the time of their isolation. The bidirectional phosphate transporter has an intrinsic dissociation constant for phosphate of 0.4 mM. Exchange mediated by this carrier is faster than unidirectional efflux of phosphate from the vacuoles. The transporter is highly selective for phosphate; of other anions tested, only arsenate is also a substrate. Transport is strongly pH-dependent with increasing activity at lower pH. Similar phosphate transport behavior was observed in right-side-out vacuolar membrane vesicles.
Booth
J W
JW
Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA. booth@hydra.rose.brandeis.edu
Guidotti
G
G
D001692:Biological Transport; D002352:Carrier Proteins / Q000378:metabolism; D028044:Phosphate-Binding Proteins; D010710:Phosphates / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D014617:Vacuoles / Q000378:metabolism*
D002352:Carrier Proteins; D028044:Phosphate-Binding Proteins; D010710:Phosphates