Forms a water-specific channel that provides the plasma membranes of renal collecting duct with high permeability to water, thereby permitting water to move in the direction of an osmotic gradient (PubMed:8429910, PubMed:7508187). Plays an essential role in renal water homeostasis (By similarity). Homotetramer. Shuttles from vesicles to the apical membrane. Vasopressin-regulated phosphorylation is required for translocation to the apical cell membrane. PLEKHA8/FAPP2 is required to transport AQP2 from the TGN to sites where AQP2 is phosphorylated. Detected in kidney, in cortical and the medullary collecting tubules (at protein level) (PubMed:8429910). Detected in kidney medulla and cortex (PubMed:8429910, PubMed:7508187). Aquaporins contain two tandem repeats each containing three membrane-spanning domains and a pore-forming loop with the signature motif Asn-Pro-Ala (NPA). Ser-256 phosphorylation is necessary and sufficient for expression at the apical membrane. Endocytosis is not phosphorylation-dependent. N-glycosylated. Belongs to the MIP/aquaporin (TC 1.A.8) family.