Caspr (contactin-associated protein) is a part of the neurexin family. It lies in the paranodal section of the myelin sheath.
It’s role is for myelin sheath attachment along with
contactin in a cis-complex (3). Caspr and Caspr2 regulate
the formation of distinct axonal domains around the nodes
of Ranvier. Caspr is required for the generation of a
membrane barrier at the paranodal junction, whereas Caspr
serves as a membrane scaffold that clusters Kv1 channels at
the juxtaparanodal region. Both interact with protein 4.1B
(4).