Contactins mediate cell surface interactions during nervous system development. May contribute to the formation of somatotopic maps of cerebellar afferents during the development of the nervous system. Interacts with INgCAM/L1 and the tenascin-R TNP protein. Does not interacts with NrCAM. Expressed by subpopulations of Purkinje cells in the cerebellum. Also expressed by one type of Purkinje cell afferents, the climbing fibers. Belongs to the immunoglobulin superfamily. Contactin family.