Molecular dissection of tight junctions.

In epithelial and endothelial cells, the tight junction (TJ) seals cells to create a primary barrier to the diffusion of solutes across the cell sheet, and it also works as a boundary between the apical and basolateral membrane domains to create their polarization. An integral membrane protein working at TJ is postulated to exist, but it has remained elusive for quite some time. Most recently, using mAbs, we identified an integral membrane protein named occludin that was exclusively localized at TJ both in epithelial and endothelial cells. Here we overview our recent studies on the structure and function of occludin.