Claudin-11 also known as CLDN11 is a member of the claudin family. Claudin-11 protein functions as a crucial component of tight junctions, essential for maintaining epithelial and endothelial barrier integrity. Tight junctions regulate paracellular transport, ensuring substances pass through spaces between cells in a controlled manner. Claudin-11 plays a vital role in the central nervous system, contributing to blood-brain barrier formation, a selective barrier protecting the brain from harmful substances while allowing essential nutrients to pass through. Claudin-11′s unique structure, including four transmembrane domains and two extracellular loops, facilitates tight junction strand formation that seals intercellular space.