Aquaporins facilitate the transport of water and small neutral solutes across cell membranes. Expression is highest in root tips, with slightly lower levels of hybridizing mRNA in stems, and whole roots, and much lower levels in nodules and leaves. 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.