Molecular structure of the apical junction complex and its contribution to the paracellular barrier

The major focus of this review is on the molecular structure and functions of proteins that are involved in the formation of tight intercellular junctions and some methods used to modulate intercellular junctions. Tight junctions are a barricade for paracellular delivery of molecules such as peptides and proteins. Understanding the molecular structure and functions of intercellular junction proteins may provide the possibility of systematically designing molecules that can regulate tight junctions. Regulation of proteins involved in the formation of intercellular junctions may open avenues to modulating the porosity of intercellular junctions to improve paracellular drug delivery.