JAM-B/CD322

JAM-B (CD322) is the second member of the junctional adhesion molecule family and is distinguished from JAM-A by its highly restricted expression: it sits in the tight junctions of high endothelial venules of peripheral lymph nodes and of specialized epithelial barriers. Its best-characterized partner is JAM-C, with which it engages heterophilically across cell junctions, and interactions with integrins have also been described. Through these contacts JAM-B contributes to lymphocyte trafficking from blood into lymphoid tissue and to the structural organization of the venular wall. Because it marks high endothelial venules, recombinant JAM-B is used to study lymphocyte homing and the endothelial biology of secondary lymphoid organs.