Contactins mediate cell surface interactions during nervous system development. Has some neurite outgrowth-promoting activity. May be involved in synaptogenesis. Interacts with PTPRG. Specifically expressed in the nervous system. Not expressed in heart, spleen, lung, liver, kidney or skeletal muscle. In the hippocampus, it is highly expressed in CA1 pyramidal cells and weakly expressed in other regions of the hippocampus. Belongs to the immunoglobulin superfamily. Contactin family.