Sugar transport across the plant vacuolar membrane: nature and regulation of carrier proteins

•The plant vacuole is the major site for sugar storage.•The activities of vacuolar sugar porters determine plant yield and stress tolerance.•The vacuole is energized by two proton pumps, the V-ATPase and the tonoplast pyrophosphatase. However, in some species a plasma membrane P3A/B type ATPase contributes in addition to the proton-motive force.•Vacuolar sugar transporters helped to identify target mechanisms allowing to direct membrane proteins to the tonoplast.