Required, with CNTNAP2, for radial and longitudinal organization of myelinated axons. Plays a role in the formation of functional distinct domains critical for saltatory conduction of nerve impulses in myelinated nerve fibers. Demarcates the paranodal region of the axo-glial junction. In association with contactin involved in the signaling between axons and myelinating glial cells. Interacts with CNTN1/contactin in cis form. Predominantly expressed in brain. Weak expression detected in ovary, pancreas, colon, lung, heart, intestine and testis. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. Belongs to the neurexin family.