Protein-coding gene in humans
Claudin-2 is a protein that in humans is encoded by the CLDN2 gene.[5][6] It belongs to the group of claudins.
Members of the claudin protein family, such as CLDN2, are expressed in an organ-specific manner and regulate the tissue-specific physiologic properties of tight junctions (Sakaguchi et al., 2002).[supplied by OMIM][6]
Function
Claudin-2 is expressed in cation-leaky epithelia such as that of the kidney proximal tubule.[7] Mice that are deficient in claudin-2 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 claudin-2 lacking cells leads to increase of permeability for small cations.[8]
Furthermore, claudin-2 has been shown to form paracellular channels for water.[9]