Claudin 4 [A12]

The claudin superfamily consists of many structurally related proteins in humans. These proteins are important structural and functional components of tight junctions in paracellular transport. Claudins are located in both epithelial and endothelial cells in all tight junction-bearing tissues. Three classes of proteins are known to localize to tight junctions, including the Claudins, Occludin and Junction adhesion molecule. Claudins, which consist of four transmembrane domains and two extracellular loops make up tight junction strands. Claudin expression is highly restricted to specific regions of different tissues and may have an important role in transcellular transport through tight junctions. Claudin-4 is not expressed in rat liver, whereas in pancreas, claudin-4 is localized to junctions of the duct epithelia and junctions of acinar cells. In the rat gut, claudin-4 displays highly restricted expression to colonic surface cells. The human claudin-4 gene maps to chromosome 7q11.23.