Cytotoxic and Regulatory T-Cell Molecule (CRTAM) is a member of Nectin family under the immunoglobulin superfamily that is expressed by activated CD8+ and NK T cells. CRTAM is found in spleen, thymus, small intestine, peripheral blood, and it is highly expressed by Purkinje cells of the cerebellum. CRTAM is a type I transmembrane glycoprotein containing one Ig-like C2-type domain and one Ig-like V-type domain in its extracellular domain, while its cytoplasmic region shows a potential class I PDZ domain. CRTAM is expressed as a homodimer on the cell surface but does not show homotypic binding in trans. The high affinity of CRTAM/IGSF4 adhesion allows CRTAM to disrupt IGSF4 homotypic interactions. IGSF4 and T cell receptor coengagement of CD8+ cells expressiong CRTAM induces increased IFNγ or IL-22 production.