The importance of the aquaporin water channels was underscored by awarding the 2003 Nobel Prize in Chemistry to Peter Agre “for the discovery of water channels”. Today, eleven mammalian proteins that belong to the aquaporin family have been identified. The proteins present a conserved structure of six transmembrane domains with intracellular N- and C-termini. 

Aquaporin 5 (AQP5) is expressed in secretory glands, lung and eye, where it works in modulating the rate of fluid release. Since a number of pathological conditions including pulmonary edema, respiratory distress syndrome and congestive heart failure are characterized by disrupted fluid transport, it has been suggested that modulation of the expression of AQP5 could be a novel modality of treatment of the above illnesses. Indeed, several studies have shown that AQP5 expression is downregulated in animal models of acute lung infection.