kontaktin

Kontaktin, often rendered as contactin in English, is a family of neuronal cell adhesion molecules in the immunoglobulin superfamily. In vertebrates, the kontaktin family comprises several genes (CNTN1–CNTN6) encoding glycosylphosphatidylinositol (GPI)-anchored extracellular proteins. They have a modular extracellular region consisting of six immunoglobulin-like domains followed by four fibronectin type III-like domains and are tethered to the outer cell surface by a GPI anchor. Expression is developmentally regulated and enriched in the central and peripheral nervous systems.

Kontaktins mediate cell–cell adhesion and signaling essential for axon guidance, neurite outgrowth, and synapse formation. They can engage in both homophilic and heterophilic interactions and commonly associate with membrane partners such as the CNTNAP family proteins and neurofascin, contributing to the organization of paranodal and nodal regions and to myelination processes. Proteolytic shedding can release soluble ectodomains that influence neighboring cells and modulate signaling in neural tissue.

Genetics and clinical relevance: Variants or altered expression of CNTN genes have been studied in relation to neurodevelopmental and psychiatric disorders, though associations are not uniformly reproduced and mechanisms remain under investigation. In model systems, disruption of individual kontaktin genes can affect nerve conduction, myelination, and synaptic connectivity. Ongoing research seeks to define their precise interaction networks and roles in neural circuit assembly, development, and plasticity.