Caspr2

Caspr2 (for Contactin-associated protein 2) is a mammalian homolog of Drosophila Neurexin IV and belongs to the Neurexin family of highly homologous neuronal cell surface proteins; other members include neurexin I (NRXN1), neurexin II (NRXN2) and neurexin III (NRXN3) and Neurexin IV (Caspr).

Caspr2 and the closely related Caspr, demarcate distinct subdomains in myelinated axons. Specifically, Caspr is present at the paranodal junctions, while Caspr2 is colocalized with Shaker-like K+ channels in the juxtaparanodal region.

Image: Caspr2 staining of perfusion fixed frozen sections of mouse brain using Human at 10 µg/mL overnight at 4 °C. Tissue was stained using the Fluoro 557-conjugated Anti-Sheep IgG Secondary Antibody (red) and counterstained with DAPI (blue).