[6] CASPR is a membrane protein found in the neuronal membrane in the paranodal section of the axon[[]] in myelinated neurons, between the Nodes of Ranvier containing Na+ channels, and juxtaparanode, which contains K+ channels.

The gene product was initially identified as a 190-kD protein associated with the contactin-PTPRZ1 complex.

Northern blot analysis showed that the gene is transcribed predominantly in brain as a transcript of 6.2 kb, with weak expression in several other tissues tested.

The architecture of its extracellular domain is similar to that of neurexins, and this protein may be the signaling subunit of contactin, enabling recruitment and activation of intracellular signaling pathways in neurons.

[9] This article incorporates text from the United States National Library of Medicine, which is in the public domain.