Juxtaparanodal clustering of Shaker-like K+ channels in myelinated axons depends on Caspr2 and TAG-1.
In myelinated axons, K+ channels are concealed under the myelin sheath in the juxtaparanodal region, where they are associated with Caspr2, a member of the neurexin superfamily. Deletion of Caspr2 in mice by gene targeting revealed that it is required to maintain K+ channels at this location. Furthermore, we show that the localization of Caspr2 and clustering of K+ channels at the juxtaparanodal region depends on the presence of TAG-1, an immunoglobulin-like cell adhesion molecule that binds Caspr2. These results demonstrate that Caspr2 and TAG-1 form a scaffold that is necessary to maintain K+ channels at the juxtaparanodal region, suggesting that axon-glia interactions mediated by these proteins allow myelinating glial cells to organize ion channels in the underlying axonal membrane.
Pubmed ID: 12963709 RIS Download
Animals | Axons | Cell Adhesion Molecules, Neuronal | Cell Communication | Contactin 2 | Gene Targeting | Membrane Proteins | Mice | Mice, Knockout | Microscopy, Electron | Mutation | Nerve Fibers, Myelinated | Nerve Tissue Proteins | Neural Conduction | Neuroglia | Potassium Channels | Ranvier's Nodes | Shaker Superfamily of Potassium Channels