Contactins mediate cell surface interactions during nervous system development. Involved in the formation of paranodal axo-glial junctions in myelinated peripheral nerves and in the signaling between axons and myelinating glial cells via its association with CNTNAP1. 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. Interaction with TNR induces a repulsion of neurons and an inhibition of neurite outgrowth (By similarity). Monomer (PubMed:2026173). Interacts with CNTNAP1 in cis form (By similarity). Binds to the carbonic-anhydrase like domain of PTPRZ1 (PubMed:20133774). Interacts with NOTCH1 and TNR. Detected in a complex with NRCAM and PTPRB (By similarity). Interacts with TASOR (By similarity). Strongly expressed in brain and in neuroblastoma and retinoblastoma cell lines. Lower levels of expression in lung, pancreas, kidney and skeletal muscle. The disease is caused by variants affecting the gene represented in this entry. Belongs to the immunoglobulin superfamily. Contactin family.