Tight junction
Cell-cell adhesion complex regulating paracellular transport in epithelia.
For laboratory and research use only — not for human consumption.
Tight junctions are apical structures between adjacent epithelial cells, composed of transmembrane proteins (claudins, occludin, junctional adhesion molecules) anchored to the actin cytoskeleton by intracellular scaffolding proteins (ZO-1, ZO-2). They selectively regulate paracellular transport of ions, water, and macromolecules. Tight-junction dysfunction underlies the 'leaky gut' phenotype seen in coeliac disease, inflammatory bowel disease, and several extra-intestinal conditions. Larazotide is the principal research peptide targeting tight junctions, acting as a zonulin antagonist; KPV and BPC-157 have indirect effects via mucosal inflammation suppression.