Tight junctions represent one mode of cell-to-cell adhesion in endothelial cell sheets, forming continuous seals around cells and serving as a physical barrier to prevent solutes and water from passing freely through the paracellular space. The protein encoded by this immunoglobulin superfamily gene member is localized in the tight junctions between high endothelial cells. It acts as an adhesive ligand for interacting with a variety of immune cell types and may play a role in lymphocyte homing to secondary lymphoid organs.[7]
It is purported to promote lymphocyte transendothelial migration.[8] It might also be involved with endothelial cell polarity, by associating to cell polarity protein PARD3 (PAR-3), together with JAM3.[9]
