Aquaporin 3 (AQP-3) belongs to a family of membrane proteins that allow passage of water and certain other solutes through biological membranes. The family is composed of 13 members (AQP-0 to AQP-12).

The aquaporins can be divided into two functional groups based on their permability characteristics: the aquaporins that are only permeated by water and the aquaglyceroporins that are permeated by water and other small solutes such as glycerol. This last group includes AQP-3 as well as AQP-7, AQP-9 and AQP-10.¹ Little is known about the function of the two newest members, AQP-11 and AQP-12.  

The proteins present a conserved structure of six transmembrane domains with intracellular N- and C-termini. The functional channel is a tetramer but each subunit has a separate pore and therefore the functional channel unit, contains four pores.¹

AQP-3 is widely expressed in several organs with prominent expression found in the skin, colon, lung and kidney. Consistent with a central function of AQP-3 in skin, mice deficient in AQP-3 have reduced skin water content and elasticity compared with wild-type mice, as well as impaired wound healing and epidermal biosynthesis.² Furthermore, AQP-3 deficient mice were found to be resistant to skin tumor development suggesting a role for this aquaporin in tumorigenesis.³