Vacuolar inositol-proton symporter involved in the release of myo-inositol from vacuoles. Not involved in glucose or fructose transport. Expressed in seedlings, leaves, flowers and pollen grains. Not detected in seeds. The C-terminal domain (465-509) is necessary and sufficient for vacuole membrane targeting. The di-Leu motif is required for this sorting. Reduced root length at low concentrations of myo-inositol. The sorting of INT1 to the tonoplast is independent of the AP-3 adapter complex but is brefeldin A sensitive. Belongs to the major facilitator superfamily. Sugar transporter (TC 2.A.1.1) family.