Recombinant Human CLDN2 protein

Claudin-2 (CLDN2), a member of the claudin family of transmembrane proteins, is a critical component of tight junctions that regulate paracellular permeability and maintain cell polarity in epithelial and endothelial tissues. Structurally, it consists of four transmembrane domains, two extracellular loops, and intracellular N- and C-termini. The second extracellular loop mediates homotypic or heterotypic interactions with other claudins to form selective paracellular channels. CLDN2 is predominantly expressed in tissues such as the intestine, liver, and kidney, where it facilitates the passive transport of small cations (e.g., Na⁺) and water, playing a vital role in ion homeostasis and barrier function. Dysregulation of CLDN2 has been implicated in multiple pathological conditions. Its overexpression is associated with increased epithelial permeability in inflammatory bowel disease (IBD), liver fibrosis, and certain cancers (e.g., colorectal and hepatocellular carcinomas), where it may promote tumor progression by enhancing cell proliferation, migration, or survival. Conversely, reduced CLDN2 expression has been observed in some autoimmune disorders. Recombinant CLDN2 proteins, typically produced in mammalian or bacterial expression systems, retain the functional domains required for structural and interaction studies. These proteins are widely used to investigate tight junction dynamics, screen therapeutic agents targeting CLDN2-mediated pathways, or develop diagnostic tools. For example, recombinant CLDN2 serves as an antigen for generating antibodies to detect disease-specific expression patterns in clinical samples. Its application in 3D cell culture models also aids in studying epithelial barrier dysfunction mechanisms. Research on CLDN2 continues to advance its potential as a biomarker or therapeutic target for diseases linked to epithelial integrity loss.