The potassium channel KAT1 is activated by plant and animal 14-3-3 proteins

J Biol Chem. 2006 Nov 24;281(47):35735-41. doi: 10.1074/jbc.M603361200. Epub 2006 Sep 21.

Abstract

14-3-3 proteins modulate the plant inward rectifier K+ channel KAT1 heterologously expressed in Xenopus oocytes. Injection of recombinant plant 14-3-3 proteins into oocytes shifted the activation curve of KAT1 by +11 mV and increased the tau(on). KAT1 was also modulated by 14-3-3 proteins of Xenopus oocytes. Titration of the endogenous 14-3-3 proteins by injection of the peptide Raf 621p resulted in a strong decrease in KAT1 current (approximately 70% at -150 mV). The mutation K56E performed on plant protein 14-3-3 in a highly conserved recognition site prevented channel activation. Because the maximal conductance of KAT1 was unaffected by 14-3-3, we can exclude that they act by increasing the number of channels, thus ruling out any effect of these proteins on channel trafficking and/or insertion into the oocyte membrane. 14-3-3 proteins also increased KAT1 current in inside-out patches, suggesting a direct interaction with the channel. Direct interaction was confirmed by overlay experiments with radioactive 14-3-3 on oocyte membranes expressing KAT1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 14-3-3 Proteins / metabolism*
  • Animals
  • Arabidopsis Proteins / metabolism
  • Arabidopsis Proteins / physiology*
  • Cell Membrane / metabolism
  • Cesium / metabolism
  • Electrophysiology / methods
  • Escherichia coli / metabolism
  • Ion Channel Gating
  • Mutation
  • Oocytes / metabolism
  • Patch-Clamp Techniques
  • Potassium Channels, Inwardly Rectifying / chemistry
  • Potassium Channels, Inwardly Rectifying / metabolism
  • Potassium Channels, Inwardly Rectifying / physiology*
  • Recombinant Proteins / chemistry
  • Xenopus
  • raf Kinases / chemistry

Substances

  • 14-3-3 Proteins
  • Arabidopsis Proteins
  • KAT1 protein, Arabidopsis
  • Potassium Channels, Inwardly Rectifying
  • Recombinant Proteins
  • Cesium
  • raf Kinases