AQP2

This gene encodes a water channel protein located in the kidney collecting tubule. It belongs to the MIP/aquaporin family, some members of which are clustered together on chromosome 12q13. Mutations in this gene have been linked to autosomal dominant and recessive forms of nephrogenic diabetes insipidus. [provided by RefSeq, Oct 2008]

Full Name

Aquaporin 2

Function

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:8140421, PubMed:7524315, PubMed:7510718, PubMed:15509592). Plays an essential role in renal water homeostasis (PubMed:8140421, PubMed:7524315, PubMed:15509592).

Biological Process

Cellular response to copper ion Source: UniProtKB
Cellular response to mercury ion Source: UniProtKB
Cellular response to water deprivation Source: Ensembl
Glycerol transport Source: UniProtKB
Metanephric collecting duct development Source: Ensembl
Protein homotetramerization Source: UniProtKB
Renal water homeostasis Source: UniProtKB
Renal water transport Source: Ensembl
Water transport Source: UniProtKB

Cellular Location

Apical cell membrane; Basolateral cell membrane; Cell membrane; Trans-Golgi network membrane; Cytoplasmic vesicle membrane. Shuttles from vesicles to the apical membrane (PubMed:15509592). Vasopressin-regulated phosphorylation is required for translocation to the apical cell membrane (PubMed:15509592). PLEKHA8/FAPP2 is required to transport AQP2 from the TGN to sites where AQP2 is phosphorylated (By similarity).

Involvement in disease

Diabetes insipidus, nephrogenic, autosomal (ANDI): A disorder caused by the inability of the renal collecting ducts to absorb water in response to arginine vasopressin. Characterized by excessive water drinking (polydipsia), excessive urine excretion (polyuria), persistent hypotonic urine, and hypokalemia. Inheritance can be autosomal dominant or recessive.

Topology

Cytoplasmic: 1-11 aa
Helical: 12-32 aa
Extracellular: 33-40 aa
Helical: 41-59 aa
Cytoplasmic: 60-64 aa
Discontinuously helical: 65-74 aa
Cytoplasmic: 75-85 aa
Helical: 86-107 aa
Extracellular: 108-127 aa
Helical: 128-148 aa
Cytoplasmic: 149-156 aa
Helical: 157-176 aa
Extracellular: 177-180 aa
Discontinuously helical: 181-193 aa
Extracellular: 194-201 aa
Helical: 202-222 aa
Cytoplasmic: 223-271 aa

PTM

Ser-256 phosphorylation is necessary and sufficient for expression at the apical membrane. Endocytosis is not phosphorylation-dependent.
N-glycosylated.