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 (By similarity). Involved in motor coordination. Interacts with PTPRG. Expressed in brain. In brain, it is preferentially expressed in the accessory olfactory bulb, layers II/III and V of the cerebral cortex, piriform cortex, anterior thalamic nuclei, locus coeruleus of the pons and mesencephalic trigeminal nucleus and in Purkinje cells of the cerebellum. Highly expressed after birth, reaching a maximum at the postnatal day 7, and declines thereafter in the cerebrum, whereas it increases in the cerebellum to adulthood. Mice are viable and fertile, the formation and organization of all nuclei and layers throughout the brains are apparently normal. They are however slow to learn to stay on the rotating rod in the rotorod test during repeated trials, and display dysfunction of equilibrium and vestibular senses in the wire hang and horizontal rod-walking tests. Belongs to the immunoglobulin superfamily. Contactin family.