Cell adhesion molecule that mediates both heterotypic cell-cell contacts via its interaction with CD6, as well as homotypic cell-cell contacts (  , ). Promotes T-cell activation and proliferation via its interactions with CD6 ( ). Contributes to the formation and maturation of the immunological synapse via its interactions with CD6 (, ). Mediates homotypic interactions with cells that express ALCAM (, ). Acts as a ligand for the LILRB4 receptor, enhancing LILRB4-mediated inhibition of T cell proliferation . Required for normal hematopoietic stem cell engraftment in the bone marrow . Mediates attachment of dendritic cells onto endothelial cells via homotypic interaction . Inhibits endothelial cell migration and promotes endothelial tube formation via homotypic interactions (, ). Required for normal organization of the lymph vessel network. Required for normal hematopoietic stem cell engraftment in the bone marrow. Plays a role in hematopoiesis; required for normal numbers of hematopoietic stem cells in bone marrow. Promotes in vitro osteoblast proliferation and differentiation (By similarity). Promotes neurite extension, axon growth and axon guidance; axons grow preferentially on surfaces that contain ALCAM. Mediates outgrowth and pathfinding for retinal ganglion cell axons (By similarity).
Inhibits activities of membrane-bound isoforms by competing for the same interaction partners. Inhibits cell attachment via homotypic interactions. Promotes endothelial cell migration. Inhibits endothelial cell tube formation.
Subcellular locations: Cell membrane, Cell projection, Axon, Cell projection, Dendrite
Detected at the immunological synapse, i.e, at the contact zone between antigen-presenting dendritic cells and T-cells (, ). Colocalizes with CD6 and the TCR/CD3 complex at the immunological synapse .
Subcellular locations: Secreted
Detected on hematopoietic stem cells derived from umbilical cord blood . Detected on lymph vessel endothelial cells, skin and tonsil . Detected on peripheral blood monocytes . Detected on monocyte-derived dendritic cells (at protein level) . Detected at low levels in spleen, placenta, liver . Expressed by activated T-cells, B-cells, monocytes and thymic epithelial cells . Isoform 1 and isoform 3 are detected in vein and artery endothelial cells, astrocytes, keratinocytes and artery smooth muscle cells . Expressed by neurons in the brain. Restricted expression in tumor cell lines. Detected in highly metastasizing melanoma cell lines .