Water channel required to facilitate the transport of water from the vacuolar compartment to the cytoplasm. Tonoplast. It is specifically located in the tonoplast of protein storage vacuoles (PSV) of the embryo and endosperm. Predominantly expressed in developing embryos (seeds). Also expressed in green siliques. Aquaporins contain two tandem repeats each containing three membrane-spanning domains and a pore-forming loop with the signature motif Asn-Pro-Ala (NPA). Belongs to the MIP/aquaporin (TC 1.A.8) family. TIP (TC 1.A.8.10) subfamily.