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Caspr2, a new member of the neurexin superfamily, is localized at the juxtaparanodes of myelinated axons and associates with K+ channels.

Rapid conduction in myelinated axons depends on the generation of specialized subcellular domains to which different sets of ion channels are localized. Here, we describe the identification of Caspr2, a mammalian homolog of Drosophila Neurexin IV (Nrx-IV), and show that this neurexin-like protein and the closely related molecule Caspr/Paranodin demarcate distinct subdomains in myelinated axons. While contactin-associated protein (Caspr) is present at the paranodal junctions, Caspr2 is precisely colocalized with Shaker-like K+ channels in the juxtaparanodal region. We further show that Caspr2 specifically associates with Kv1.1, Kv1.2, and their Kvbeta2 subunit. This association involves the C-terminal sequence of Caspr2, which contains a putative PDZ binding site. These results suggest a role for Caspr family members in the local differentiation of the axon into distinct functional subdomains.

Pubmed ID: 10624965


  • Poliak S
  • Gollan L
  • Martinez R
  • Custer A
  • Einheber S
  • Salzer JL
  • Trimmer JS
  • Shrager P
  • Peles E



Publication Data

December 27, 1999

Associated Grants

  • Agency: NINDS NIH HHS, Id: NS17965
  • Agency: NINDS NIH HHS, Id: NS34383
  • Agency: NINDS NIH HHS, Id: NS38208

Mesh Terms

  • Amino Acid Sequence
  • Animals
  • Axons
  • Blotting, Northern
  • Fluorescent Antibody Technique, Indirect
  • Humans
  • Immunohistochemistry
  • Kv1.1 Potassium Channel
  • Membrane Proteins
  • Mice
  • Microscopy, Electron
  • Molecular Sequence Data
  • Nerve Fibers, Myelinated
  • Nerve Tissue Proteins
  • Nervous System
  • Potassium Channels
  • Potassium Channels, Voltage-Gated
  • Precipitin Tests
  • Rats