KCNQ1/KCNE1 assembly, co-translation not required

Channels (Austin). Mar-Apr 2010;4(2):108-14. doi: 10.4161/chan.4.2.11141. Epub 2010 Mar 6.

Abstract

Voltage-gated potassium channels are often assembled with accessory proteins that increase their functional diversity. KCNE proteins are small accessory proteins that modulate voltage-gated potassium (K(V)) channels. Although the functional effects of various KCNE proteins have been described, many questions remain regarding their assembly with the pore-forming subunits. For example, while previous experiments with some K(V) channels suggest that the association of the pore-subunit with the accessory subunits occurs co-translationally in the endoplasmic reticulum, it is not known whether KCNQ1 assembly with KCNE1 occurs in a similar manner to generate the medically important cardiac slow delayed rectifier current (I(Ks)). In this study we used a novel approach to demonstrate that purified recombinant human KCNE1 protein (prKCNE1) modulates KCNQ1 channels heterologously expressed in Xenopus oocytes resulting in generation of I(Ks). Incubation of KCNQ1-expressing oocytes with cycloheximide did not prevent I(Ks) expression following prKCNE1 injection. By contrast, incubation with brefeldin A prevented KCNQ1 modulation by prKCNE1. Moreover, injection of the trafficking-deficient KCNE1-L51H reduced KCNQ1 currents. Together, these observations indicate that while assembly of KCNE1 with KCNQ1 does not require co-translation, functional KCNQ1-prKCNE1 channels assemble early in the secretory pathway and reach the plasma membrane via vesicular trafficking.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Brefeldin A / pharmacology
  • Cell Membrane / metabolism
  • Cycloheximide / pharmacology
  • Endoplasmic Reticulum
  • Humans
  • Ion Channel Gating* / drug effects
  • KCNQ1 Potassium Channel / biosynthesis
  • KCNQ1 Potassium Channel / drug effects
  • KCNQ1 Potassium Channel / genetics
  • KCNQ1 Potassium Channel / metabolism*
  • Kinetics
  • Membrane Potentials
  • Potassium / metabolism*
  • Potassium Channels, Voltage-Gated / biosynthesis
  • Potassium Channels, Voltage-Gated / drug effects
  • Potassium Channels, Voltage-Gated / genetics
  • Potassium Channels, Voltage-Gated / metabolism*
  • Protein Synthesis Inhibitors / pharmacology
  • Protein Transport
  • Recombinant Proteins / metabolism
  • Xenopus laevis

Substances

  • KCNE1 protein, human
  • KCNQ1 Potassium Channel
  • KCNQ1 protein, human
  • Potassium Channels, Voltage-Gated
  • Protein Synthesis Inhibitors
  • Recombinant Proteins
  • Brefeldin A
  • Cycloheximide
  • Potassium