Opioid-binding Cell Adhesion Molecule (OBCAM), also designated OPCML, is a protein that binds opioid alkaloids in the presence of acidic lipids. It is a GPI-anchored cell adhesion molecule that is part of the immunoglobulin (Ig) domain-containing superfamily. It also belongs to the IgLON family based on the initials of the 3 family members, LAMP, OBCAM, and Neurotrimin. These molecules interact homophilically and heterophilically within the family either to promote or inhibit neurite outgrowth.