Molecular microdomains in a sensory terminal, the vestibular calyx ending

J Neurosci. 2011 Jul 6;31(27):10101-14. doi: 10.1523/JNEUROSCI.0521-11.2011.

Abstract

Many primary vestibular afferents form large cup-shaped postsynaptic terminals (calyces) that envelope the basolateral surfaces of type I hair cells. The calyceal terminals both respond to glutamate released from ribbon synapses in the type I cells and initiate spikes that propagate to the afferent's central terminals in the brainstem. The combination of synaptic and spike initiation functions in these unique sensory endings distinguishes them from the axonal nodes of central neurons and peripheral nerves, such as the sciatic nerve, which have provided most of our information about nodal specializations. We show that rat vestibular calyces express an unusual mix of voltage-gated Na and K channels and scaffolding, cell adhesion, and extracellular matrix proteins, which may hold the ion channels in place. Protein expression patterns form several microdomains within the calyx membrane: a synaptic domain facing the hair cell, the heminode abutting the first myelinated internode, and one or two intermediate domains. Differences in the expression and localization of proteins between afferent types and zones may contribute to known variations in afferent physiology.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Afferent Pathways / physiology
  • Animals
  • Ankyrins / metabolism
  • Calbindin 2
  • Carrier Proteins / metabolism
  • Cell Adhesion Molecules / metabolism
  • Cell Adhesion Molecules, Neuronal / metabolism
  • Ether-A-Go-Go Potassium Channels / metabolism
  • Female
  • Hair Cells, Vestibular / classification
  • Hair Cells, Vestibular / metabolism*
  • Imaging, Three-Dimensional
  • Male
  • Membrane Microdomains / metabolism*
  • Membrane Microdomains / ultrastructure
  • Microfilament Proteins / metabolism
  • Microscopy, Confocal / methods
  • Microscopy, Immunoelectron / methods
  • Myelin Basic Protein / metabolism
  • NAV1.1 Voltage-Gated Sodium Channel
  • Nerve Growth Factors / metabolism
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism
  • Potassium Channels, Voltage-Gated / metabolism
  • Protein Structure, Tertiary / physiology
  • Rats
  • Rats, Long-Evans
  • S100 Calcium Binding Protein G / metabolism
  • Sodium Channels / genetics
  • Sodium Channels / metabolism
  • Synapses / metabolism*
  • Synapses / ultrastructure
  • Tenascin / metabolism
  • Vestibular Nerve / cytology*

Substances

  • Ank2 protein, rat
  • Ankyrins
  • Calbindin 2
  • Carrier Proteins
  • Cell Adhesion Molecules
  • Cell Adhesion Molecules, Neuronal
  • Cntnap1 protein, rat
  • Ether-A-Go-Go Potassium Channels
  • Kcnh6 protein, rat
  • Mbp protein, rat
  • Microfilament Proteins
  • Myelin Basic Protein
  • NAV1.1 Voltage-Gated Sodium Channel
  • Nerve Growth Factors
  • Nerve Tissue Proteins
  • Nfasc protein, rat
  • Potassium Channels, Voltage-Gated
  • S100 Calcium Binding Protein G
  • Scn1a protein, rat
  • Sodium Channels
  • Tenascin
  • fodrin