Tight junction protein (TJ protein)

Tight junction proteins are a diverse group of molecules that form the tight junctions—specialized multiprotein complexes located at the apical region between adjacent epithelial or endothelial cells. These proteins create a selective barrier that regulates the passage of ions, water, and solutes through the paracellular pathway. The main families include claudins, occludin, tricellulin, marvelD3 (all transmembrane proteins), as well as scaffolding proteins like zonula occludens 1 (ZO‑1). Tight junctions are essential for maintaining cell polarity by separating apical and basolateral membrane domains and play key roles in tissue homeostasis by controlling permeability. They also participate in signaling pathways influencing cell differentiation and proliferation. Disruption or dysregulation of tight junction proteins is implicated in various diseases such as cancer and inflammatory conditions.

Other names

Zonula occludens proteinOccludinClaudinJunctional adhesion molecule (JAM)TricellulinMarvelD3Angulin