Claudin

Claudins are a family of proteins which, along with occludin, are the most important components of the tight junctions (zonulae occludentes).

[1][2] Tight junctions establish the paracellular barrier that controls the flow of molecules in the intercellular space between the cells of an epithelium.

Claudins are small (20–24/27 kilodalton (kDa))[5] transmembrane proteins which are found in many organisms, ranging from nematodes to human beings.

[7] The N-terminal end is usually very short (1–10 amino acids)[10][8] It is located in the cytoplasm where it is thought to help to contribute to cell signaling, cytoskeletal organization and other possible functions.

[7] Claudins were first named in 1998 by Japanese researchers Mikio Furuse and Shoichiro Tsukita at Kyoto University.

[12] The name claudin comes from Latin word claudere ("to close"), suggesting the barrier role of these proteins.

[13] A chimeric claudin was synthesized to help enhance the understanding of both the structure and function of the tight junction.