Anti-Claudin-4, Clone A-12

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Claudin-4 (Clostridium perfringens enterotoxin receptor) belongs to the 20-member family of claudins, transmembrane cellular adhesion proteins localized at epithelial and endothelial tight junctions. It is a 209 amino acid molecule with four transmembrane segments. These are essential components of tight junction charge-specific channels that regulate paracellular ion flux. It plays a role in internal organ epithelial tissue development and function during pre- and postnatal life.Phosphorylation of Claudin-4 regulates paracellular epithelial permeability. The overexpression of Claudin-4 has been shown to decrease paracellular electrical conductance due to a selective decrease in Na+ permeability, with no significant decrease in Cl-permeability. It is also up-regulated in several carcinomas.Expression of Claudin-4 has been associated with either poor prognosis or a more favorable diagnosis, depending on the type of cancer. In ovarian carcinoma cells, Claudin-3 and Claudin-4 exhibit upregulation at both mRNA and protein levels. Claudin-4 is also overexpressed in pancreatic cancer tissues and cell lines, and in other epithelial cancers. Claudin-4 has been shown to distinguish adenocarcinomas from malignant mesothelioma with 99% specificity in malignant effusions. Basal-like tumors also demonstrated overexpression of Claudin-4.