Forms a water-specific channel. May be involved in the transfer of excess sap dietary water from the initial midgut to the terminal midgut and the proximal part of the malpighian tubules. Homotetramer. Filter chamber epithelium in the digestive tract. Absent from midgut. 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. Liquid states - Issue 36 of July 2003