Contactins mediate cell surface interactions during nervous system development. Has some neurite outgrowth-promoting activity in the cerebral cortical neurons but not in hippocampal neurons. Probably involved in neuronal activity in the auditory system. Interacts with PTPRG. Specifically expressed in the nervous system. Expressed in cerebrum and cerebellum but at low level in spinal chord. In brain, it is expressed in highly restricted regions at postnatal day 7, such as the auditory pathway, including the cochlear nucleus, superior olive, inferior colliculus, medial geniculate nucleus and auditory cortex. Expressed in the accessory olfactory bulb, glomerular and mitral cell layers in the olfactory bulb, anterior thalamic nuclei, layers II-IV of the cerebral cortex, dentate gyrus of the hippocampus and external granule cells and Purkinje cells of the cerebellum. Also expressed in the piriform cortex, inferior olive and facial nucleus. Weakly or not expressed in other parts of the brain. Expressed after birth, reaching a maximum at postnatal day 14 in the cerebrum and postnatal day 3 in the cerebellum. Then, it decreases abruptly thereafter (at protein level). Belongs to the immunoglobulin superfamily. Contactin family.