Abstract
We examined the localization of Caspr and the K(+) channels Kv1.1 and Kv1.2, all of which are intrinsic membrane proteins of myelinated axons in the PNS. Caspr is localized to the paranode; Kv1. 1, Kv1.2 and their beta2 subunit are localized to the juxtaparanode. Throughout the internodal region, a strand of Caspr staining is flanked by a double strand of Kv1.1/Kv1.2/Kvbeta2 staining. This tripartite strand apposes the inner mesaxon of the myelin sheath, and forms a circumferential ring that apposes the innermost aspect of Schmidt-Lanterman incisures. The localization of Caspr and Kv1.2 are not disrupted in mice with null mutations of the myelin associated glycoprotein, connexin32, or Kv1.1 genes. At all of these locations, Caspr and Kv1.1/Kv1.2/Kvbeta2 define distinct but interrelated domains of the axonal membrane that appear to be organized by the myelin sheath.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Cell Adhesion Molecules, Neuronal*
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Cell Communication / physiology
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Connexins / genetics
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Gap Junction beta-1 Protein
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Gene Expression
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Kv1.1 Potassium Channel
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Kv1.2 Potassium Channel
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Mice
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Mice, Knockout
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Microscopy, Confocal
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Myelin Sheath / physiology*
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Myelin-Associated Glycoprotein / genetics
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Nerve Fibers / chemistry*
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Neurons / chemistry
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Neurons / ultrastructure
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Potassium Channels / analysis*
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Potassium Channels / genetics
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Potassium Channels, Voltage-Gated*
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Ranvier's Nodes
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Rats
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Receptors, Cell Surface / analysis*
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Schwann Cells / cytology
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Schwann Cells / physiology*
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Sciatic Nerve / chemistry
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Sciatic Nerve / cytology
Substances
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Cell Adhesion Molecules, Neuronal
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Cntnap1 protein, mouse
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Cntnap1 protein, rat
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Connexins
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Kcna1 protein, mouse
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Kcna2 protein, mouse
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Kcna2 protein, rat
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Kv1.2 Potassium Channel
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Myelin-Associated Glycoprotein
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Potassium Channels
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Potassium Channels, Voltage-Gated
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Receptors, Cell Surface
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Kv1.1 Potassium Channel