Aquaporin-2 (AQP2)

Aquaporin-2 (AQP2) is a membrane-bound water channel protein primarily expressed in the principal cells of the kidney collecting duct, where it is essential for regulating the body's water balance and concentrating urine. AQP2 is uniquely regulated by the hormone arginine vasopressin (antidiuretic hormone), which controls its trafficking between intracellular vesicles and the apical plasma membrane. Upon vasopressin stimulation, AQP2-containing vesicles fuse with the membrane, permitting increased water permeability and reabsorption. Loss-of-function mutations in AQP2 cause nephrogenic diabetes insipidus, a condition characterized by excessive urination and thirst[1][2][3][4][5][6][7][9]. Dysregulation of AQP2 is also implicated in multiple clinical states involving water imbalance, such as heart failure and liver cirrhosis. Structurally, AQP2 forms a tetramer with each protomer containing six transmembrane helices and a selective water pore[1][2][8]. No drugs directly target AQP2, but compounds modulating vasopressin signaling upstream (like desmopressin) affect its activity and membrane expression.

Other names

Aquaporin 2AQP2vasopressin-regulated water channelwater channel protein AQP2

Drugs such as vasopressin analogs act via the vasopressin V2 receptor to increase AQP2 membrane insertion, enhancing water reabsorption[3][9]