CLC transport proteins in plants

Nitrate compartmentalization in intracellular organelles has been long recognized as critical for plant physiology but the molecular identity of the proteins involved remained unclear for a long time. In Arabidopsis thaliana  , AtClC-a has been recently shown to be a NO3-/H+ antiporter critical for nitrate transport into the vacuoles. AtClC-a is a member of the CLC protein family, whose animal and bacterial members, comprising both channels and H+-coupled antiporters, have been previously implicated exclusively in Cl− transport. Despite the different NO3- over Cl− selectivity of AtClC-a compared to the other CLC antiporters, it has similar transport properties.Other CLC homologues have been cloned in Arabidopsis, tobacco, rice and soybean.