Endothelial cell-selective adhesion molecule (ESAM) is a member of JAM family of immunoglobulin superfamily and consists of one V-type and one C2-type immunoglobulin domain, as well as a hydrophobic signal sequence, a single transmembrane region, and a cytoplasmic domain. It is specifically expressed at endothelial tight junctions and on activated platelets. ESAM at endothelial tight junctions participates in the migration of neutrophils through the vessel wall, possibly by influencing endothelial cell contacts. The adaptor protein membrane-associated guanylate kinase MAGI-1 has been identified as an intracellular binding partner of ESAM. Previous studies have indicated that ESAM regulates angiogenesis in the primary tumor growth and endothelial permeability. It suggest that ESAM has a redundant functional role in physiological angiogenesis but serves a unique and essential role in pathological angiogenic processes such as tumor growth.

> 95% as determined by SDS-PAGE