[The CIC chloride channels and their role in plant cell]

The chloride channel superfamily (CIC) is the large group of anion transporters expressed in nearly every cell of eukaryotic as well as prokaryotic organisms. Functionally, CIC proteins can be divided into two classes: anion channels and secondary-active anion/proton transporters. Proteins from both classes are two-pore homodimers with monomers forming an individual anion-permeation pathway and key residues for ion binding and selectivity. Most CIC's have also large C-termini cytosolic domains containing two cystathionine beta-synthetase domains (CBS) that are crucial for regulation of their activity. In plant cell, CIC proteins are present in membranes of various organelles including vacuole, Golgi and chloroplast. Although most of them is involve in Cl(-) transport, recent studies on Arabidopsis thaliana have revealed that at least tonoplast AtClCa can act as a NO3(-)/H+ exchanger, suggesting the role of proteins from CIC family also in nitrate transport. Here we summarize recent advances in the molecular characterization of this family and its role in plants, especially in NO3(-) distribution within the cell.