Aquaporin 1 (AQP-1) 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. AQP-1 together with AQP-2, AQP-4 and AQP-5 belongs to the first group.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-1 is widely expressed in several organs with prominent expression found in kidney, lung, red blood cells intestine and brain. Studies with mice lacking AQP-1 show that the channel has a critical role in urine concentration.2 In addition, AQP-1 expression in tumor cells was shown to contribute to enhanced tumor spread and metastatic potential.3
