Open-channel block by the cytoplasmic tail of sodium channel beta4 as a mechanism for resurgent sodium current

Neuron. 2005 Jan 20;45(2):233-44. doi: 10.1016/j.neuron.2004.12.035.


Voltage-gated sodium channels with "resurgent" kinetics are specialized for high-frequency firing. The alpha subunits interact with a blocking protein that binds open channels upon depolarization and unbinds upon repolarization, producing resurgent sodium current. By limiting classical inactivation, the cycle of block and unblock shortens refractory periods. To characterize the blocker in Purkinje neurons, we briefly exposed inside-out patches to substrate-specific proteases. Trypsin and chymotrypsin each removed resurgent current, consistent with established roles for positively charged and hydrophobic/aromatic groups in blocking sodium channels. In Purkinje cells, the only known sodium channel-associated subunit that has a cytoplasmic sequence with several positive charges and clustered hydrophobic/aromatic residues is beta4 (KKLITFILKKTREK; beta4(154-167)). After enzymatic removal of block, beta4(154-167) fully reconstituted resurgent current, whereas scrambled or point-mutated peptides were ineffective. In CA3 pyramidal neurons, which lack beta4 and endogenous block, beta4(154-167) generated resurgent current. Thus, beta4 may be the endogenous open-channel blocker responsible for resurgent kinetics.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cell Membrane / physiology*
  • Hippocampus / physiology
  • Ion Channel Gating / physiology*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mutation / physiology
  • Patch-Clamp Techniques
  • Peptide Hydrolases / pharmacology
  • Peptides / chemistry
  • Peptides / genetics
  • Peptides / pharmacology
  • Protein Structure, Tertiary / physiology
  • Protein Subunits / chemistry*
  • Protein Subunits / genetics*
  • Protein Subunits / physiology
  • Purkinje Cells / physiology*
  • Pyramidal Cells / physiology
  • Sodium Channels / chemistry*
  • Sodium Channels / genetics*
  • Sodium Channels / physiology
  • Voltage-Gated Sodium Channel beta-4 Subunit


  • Peptides
  • Protein Subunits
  • SCN4B protein, human
  • Scn4b protein, mouse
  • Sodium Channels
  • Voltage-Gated Sodium Channel beta-4 Subunit
  • Peptide Hydrolases