Contactins mediate cell surface interactions during nervous system development. Participates in oligodendrocytes generation by acting as a ligand of NOTCH1. Its association with NOTCH1 promotes NOTCH1 activation through the released notch intracellular domain (NICD) and subsequent translocation to the nucleus. Involved in motor coordination. Tissue specificity: Expressed in nervous system. Highly expressed in cerebellum. Expressed at intermediate level in thalamus, subthalamic nucleus. Weakly expressed in corpus callosum, caudate nucleus and spinal cord. Similarity: Belongs to the immunoglobulin superfamily. Contactin family. Contains 4 fibronectin type-III domains. Contains 6 Ig-like C2-type (immunoglobulin-like) domains.