MOLECULAR MECHANISMS AND INTERACTIONS AT THE NODE OF RANVIER: A STRUCTURAL PERSPECTIVE

Abstract

Action potentials are conducted along axons in a saltatory fashion, being reinforced periodically at the nodes of Ranvier (NOR), where there is a gap in the myelin sheath that covers the axon. The NOR is organized into multiple compartments. The electrical signal is boosted via ion channels at the nodal gap, which in turn are supported by adhesion proteins and the cytoskeleton. The septate-like paranodal junctions, formed by a protein complex that mediates the axon-glia contact, separates the components of the nodal gap from those of the juxtaparanode, where other adhesion proteins and ion channels are located underneath the myelin. Disruption of the NOR may cause a wide range of neurological diseases. While the molecular mechanisms and interactions at the NOR have been studied extensively in cell biology research, the structural biology perspective has only recently gained more attention with the publication of structures of ion channels and adhesion and cytoskeletal proteins. Here, I review the molecular mechanisms and interactions at the NOR in light of available structural data on its molecular components, particularly voltage and mechanosensitivity of ion channels. Future study of the molecular structures, especially in situ, will further increase our understanding of the (dys)function of the NOR.