Recombinant Mouse JAM-A Fc Chimera Protein, CF

The family of junctional adhesion molecules (JAM), comprising at least three members, are type I transmembrane receptors belonging to the immunoglobulin (Ig) superfamily (1, 2). These proteins are localized in the tight junctions between endothelial or epithelial cells. Some family members are also found on blood leukocytes and platelets. Mouse JAM-A is predominantly expressed at intercellular junctions of both epithelial cells and endothelial cells (3). It is also expressed on circulating megakaryocytes. Mouse JAM-A cDNA predicts a 300 amino acid (aa) residue precursor protein with a putative 23 aa signal peptide, a 215 aa extracellular region containing two Ig-like V-subset domains, a 17 aa transmembrane domain and a 45 aa cytoplasmic domain. The human and mouse protein share approximately 67% aa sequence homology. Mouse JAM-A also shares approximately 35% aa sequence homology with mouse JAM-B or JAM-C. JAM-A exhibits homotypic interactions to regulate tight junction assembly and modulate paracellular permeability (1 - 3). The human JAM-A homotypic interation also mediates platelet aggregation and adhesion to endothelial cells and may play a role in thrombosis (4). JAM-A is involved in leukocyte adhesion and transmigration through the endothelium (3, 5). JAM-A has also been shown to bind reovirus attachment protein sigma-1 to permit reovirus infection and signal virus-induced apoptosis (6).