Caspr2: ProductsContactin-associated protein 2 (Caspr2) is a neuronal membrane protein and member of the neurexin family. Caspr2 is the mammalian homolog of Drosophila Neurexin IV. Caspr2 is believed to be involved in the local differentiation of the axon into distinct functional subdomains. Studies have shown that Caspr2 is essential for clustering of Shaker-type K+ channels in the juxtaparanodes of Ranvier. This effect is dependent on the association of Caspr2 with TAG-1, a glycosyl-phosphatidyl-inositol-anchored cell adhesion molecule. Mutations in Caspr2 are associated with the development of autism and related disorders.