The Kv4.2 N-terminal restores fast inactivation and confers KChlP2 modulatory effects on N-terminal-deleted Kv1.4 channels

Pflugers Arch. 2004 Dec;449(3):235-47. doi: 10.1007/s00424-004-1328-8.

Abstract

The N-terminal end of the subunits of the voltage-gated K+ channel Kv1.4 is essential for their rapid N-type inactivation, but removal of the entire Kv4.2 N-terminus slows inactivation only moderately. In this study, we investigated the effect of substituting the Kv4.2 N-terminal for that of Kv1.4 subunits. Despite the minor role of the Kv4.2 N-terminal in Kv4.2 inactivation and the limited degree of amino acid identity between Kv1.4 and Kv4.2 N-terminals, attachment of the Kv4.2 N-terminal to inactivation-deficient, N-terminal-deleted Kv1.4 subunits restored rapid inactivation. The Kv4.2 N-terminal/N-deleted Kv1.4 chimeric construct had inactivation kinetics like those of Kv4.2, inactivation voltage-dependence resembling Kv1.4 and recovery from inactivation substantially faster than wild-type Kv1.4. Acceleration of reactivation appeared to be due to the ability of chimeric channels to recover from inactivation without passing through the open state. Co-expression of wild-type Kv1.4 with the K+ channel interacting protein-2 (KChIP2) did not alter Kvl.4 properties, but co-expression of KChIP2 with Kv4.2 N-terminal/N-deleted Kv1.4 chimeric subunits significantly increased current expression and slowed inactivation without altering the rate of recovery from inactivation. We conclude that substitution of the Kv4.2 N-terminal for that of Kv1.4 transfers a variety of properties of Kv4.2, including inactivation time-dependence, accelerated recovery from inactivation and interaction with KChIP2, to Kv1.4, indicating the ability of Kvl.4 subunits to display these properties and the sufficiency of the Kv4.2 N-terminal to convey them.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • COS Cells
  • Calcium-Binding Proteins / chemistry
  • Calcium-Binding Proteins / metabolism*
  • Chlorocebus aethiops
  • Ion Channel Gating / physiology*
  • Kv Channel-Interacting Proteins
  • Kv1.4 Potassium Channel
  • Membrane Potentials / physiology*
  • Potassium / metabolism*
  • Potassium Channels, Voltage-Gated / chemistry
  • Potassium Channels, Voltage-Gated / metabolism*
  • Protein Structure, Tertiary
  • Protein Subunits
  • Recombinant Proteins / metabolism
  • Shal Potassium Channels
  • Structure-Activity Relationship

Substances

  • Calcium-Binding Proteins
  • Kv Channel-Interacting Proteins
  • Kv1.4 Potassium Channel
  • Potassium Channels, Voltage-Gated
  • Protein Subunits
  • Recombinant Proteins
  • Shal Potassium Channels
  • Potassium