Mediates homophilic cell-cell adhesion (By similarity). Minor component of the myelin sheath. May be involved in completion and/or maintenance of the myelin sheath and in cell-cell communication. Homodimer. Found exclusively in the CNS, where it is localized on the surface of myelin and oligodendrocyte cytoplasmic membranes. Belongs to the immunoglobulin superfamily. BTN/MOG family. Do not confuse myelin-oligodendrocyte glycoprotein (MOG) with oligodendrocyte-myelin glycoprotein (OMG).