Description
Claudin-2 is expressed in cation-leaky epithelia such as that of the kidney proximal tubule. Mice that are deficient in the protein have reduced reabsorption of Na+ in the proximal tubule, consistent with a role in paracellular transport. Similar results have been obtained with cultured cells, as overexpression in CLDN2 lacking cells leads to increase of permeability for small cations. Furthermore, CLDN2 has been shown to form paracellular channels for water. [Wiki]