Junctional Adhesion Molecule A (JAM-A) is a single-pass type I membrane protein that belongs to the immunoglobulin superfamily. JAM-A contains 2 Ig-like V-type (immunoglobulin-like) domains and Interacts with the ninth PDZ domain. JAM-A is localized to the tight junctions of both epithelial and endothelial cells. JAM-A seems to be involved in epithelial tight junction formation. JAM-A appears early in primordial forms of cell junctions and recruits PARD3. The association of the PARD6-PARD3 complex may prevent the interaction of PARD3 with JAM-A, thereby preventing tight junction assembly. JAM-A plays a role in regulating monocyte transmigration involved in regulating integrity of the epithelial barrier. In the case of orthoreovirus infection, JAM-A serves as receptor for the virus.