JAML is a 394 amino acid single-pass type I membrane protein and novel adhesion molecule with localization at the cell plasma membrane in regions of cell-to-cell contact but not free cell borders, implying that JAML participates in homophilic interactions. JAML belongs to the immunoglobulin superfamily and is expressed in peripheral blood leukocytes, bone marrow, spleen, lymph nodes and fetal thymus, liver and spleen. JAML assists in the migration of leukocytes through endothelilal and epithelial tissues, mediates binding with CAR (coxsackie and adenovirus receptor) via its Ig-like V-type domain 2, and strengthens the binding of leukocytes to endothelial cells. Consisting of a transmembrane segment, cytoplasmic tail, 19-amino acid signal peptide and two extracellular immunoglobulin-like domains, JAML also undergoes alternative splicing resulting in three isoforms and is encoded by a gene mapping to human chromosome 11q23.3.