A family of integral membrane proteins that have four transmembrane domains and are important structural components of tight junctions where they occlude the intercellular space. There are 24 human claudins that are expressed in a tissue-specific pattern. Claudin-1 (senescence-associated epithelial membrane protein, 211 aa) forms homopolymers and heteropolymers with some other claudins. It is also a coreceptor for hepatitis C entry into liver cells. Mutations in the claudin-1 gene are the cause of ichthyosis-sclerosing cholangitis neonatal syndrome. Mutations in claudin-14 are associated with autosomal recessive deafness-29. Mutations in claudin-19 cause a form of renal magnesium wasting with hypercalcinosis and progressive renal failure and severe ocular involvement. See paracellin (paracellin-1).
Subjects: Medicine and Health.