Putatively gated water-specific channel, requiring a cysteine residue within the channel. Impermeable to water, glycerol and urea when expressed in Xenopus oocytes. Not regulated by pH; channels remain impermeable to water at pH 7.4 and 5.2. Expressed in lamellipodia-like protrusions of the plasma membrane and intracellular vacuolar structures. Expressed throughout development from amoebae through to the formation of spores at 24 hours. Highest expression is at 12 and 24 hours. Inhibited by mercuric chloride. Aquaporins contain two tandem repeats each containing three membrane-spanning domains and a pore-forming loop with the signature motif Asn-Pro-Ala (NPA). Glycosylated and non-glycosylated forms exist throughout all developmental stages. Belongs to the MIP/aquaporin (TC 1.A.8) family.