text: The molecular organization of the nodes corresponds to their specialized function in impulse propagation.  The level of sodium channels in the node versus the internode suggests that the number IMPs corresponds to sodium channels.  Potassium channels are essentially absent in the nodal axolemma, whereas they are highly concentrated in the paranodal axolemma and Schwann cell membranes at the node. The exact function of potassium channels have not quite been revealed, but it is known that they may contribute to the rapid repolarization of the action potentials or play a vital role in buffering the potassium ions at the nodes.  This highly asymmetric distribution of voltage-gated sodium and potassium channels is in striking contrast to their diffuse distribution in unmyelinated fibers.
  The filamentous network subjacent to the nodal membrane contains cytoskeletal proteins called spectrin and ankyrin.  The high density of ankyrin at the nodes may be functionally significant because several of the proteins that are populated at the nodes share the ability to bind to ankyrin with extremely high affinity.  All of these proteins, including ankyrin, are enriched in the initial segment of axons which suggests a functional relationship.  Now the relationship of these molecular components to the clustering of sodium channels at the nodes is still not known.  Although some cell-adhesion molecules have been reported to be present at the nodes inconsistently; however, a variety of other molecules are known to be highly populated at the glial membranes of the paranodal regions where they contribute to its organization and structural integrity.