Aquaporins facilitate the transport of water and small neutral solutes across cell membranes. By water stress, heat shock and to a small extent by abscisic acid (ABA). Induced within 30 min after the loss of leaf turgor. 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. PIP (TC 1.A.8.11) subfamily.