Aquaporins: a family of highly regulated multifunctional channels.
Aquaporins (AQPs) were discovered as channels facilitatingwater movement across cellular membranes. Whereas much of the research has focused on characterizing AQPs with respect to cell water homeostasis, recent discoveries in terms of the transport selectivity of AQP homologs has shed new light on their physiological roles. In fact, whereas some AQPs behave as "strict" water channels, others can conduct a wide range ofnonpolar solutes, such as urea or glycerol and even more unconventional permeants, such as the nonpolar gases carbon dioxide and nitric oxide, the polar gas ammonia, the reactive oxygen species hydrogen peroxide and the metalloids antimonite, arsenite, boron and silicon. This suggests that AQPs are also key players in various physiological processes not related to water homeostasis. The function, regulation and biological importance of AQPs in the different kingdoms is reviewed in this chapter, with special emphasis on animal and plant AQPs.
Hachez
Charles
C
Institut des Sciences de la Vie, Universit4 catholique de Louvain, Croix du Sud 5-15, B-1348 Louvain-la-Neuve, Belgium.
Chaumont
François
F
D000818:Animals; D020346:Aquaporins / Q000378:metabolism / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism; D006706:Homeostasis; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D008954:Models, Biological; D009865:Oocytes / Q000166:cytology; D010766:Phosphorylation; D010944:Plants / Q000378:metabolism; D013053:Spectrophotometry / Q000379:methods; D013347:Subcellular Fractions; D014867:Water / Q000737:chemistry; D014981:Xenopus
D020346:Aquaporins; D014867:Water