May play a role in the initial growth and guidance of axons. May be involved in cell adhesion. In conjunction with another transmembrane protein, CNTNAP2, contributes to the organization of axonal domains at nodes of Ranvier by maintaining voltage-gated potassium channels at the juxtaparanodal region (By similarity). Attached to the neuronal membrane by a GPI-anchor and is also released from neurons. In neural tissues in embryos, and in adult brain, spinal cord and cerebellum. Transiently expressed on a subset of axons in the developing rat nervous system. Belongs to the immunoglobulin superfamily. Contactin family.