CD323, also known as JAM3 and JAM-C, is a member of the junctional adhesion member family and plays a role in leukocyte migration. It is a type I transmembrane protein and is involved in cell-cell adhesion by forming homotypic or heterotypic molecules with JAM family members or integrins. CD323 is expressed in intestinal epithelial cells and is a component of epithelial desmosomes, endothelial cells, and platelets. It is expressed at low levels on T cells and is upregulated upon activation. Due to their presence in tight junction and lateral membranes, JAMs are candidate receptors for leukocytes to use when they migrate. Thrombin induces localization of JAM3 in the tight junctions, whereas angiopoietin-1 prevents JAM3 localization.