C-terminal interaction of KCNQ2 and KCNQ3 K+ channels

J Physiol. 2003 Apr 15;548(Pt 2):353-60. doi: 10.1113/jphysiol.2003.040980. Epub 2003 Mar 14.


Coexpression of KCNQ2 and KCNQ3 channels results in a 10-fold increased current amplitude compared to that of KCNQ2 alone, suggesting the formation of heteromultimeric channels. There is no interaction of either channel with KCNQ1. We evaluated the C-terminus as a potential interaction domain by construction of chimeras with interchanged C-termini of KCNQ1, KCNQ2 and KCNQ3 and functional expression in Xenopus oocytes. The chimera of KCNQ1 with a KCNQ2 C-terminus (Q1ctQ2) showed an 8-fold increase in current amplitude, and Q1ctQ3 a 3-fold increase when coexpressed with KCNQ3 and KCNQ2, respectively, indicating that the C-terminus contains an interaction domain. To characterize this interacting region, we studied further chimeras of KCNQ1 containing different parts of the KCNQ3 C-terminus for interaction with KCNQ2. We also evaluated short sequences of the KCNQ2 C-terminus for a dominant-negative effect on Q1ctQ3. According to the results of these experiments, functional interaction of KCNQ2 and KCNQ3 requires a highly conserved region of about 80 amino acids, previously called the A-domain, plus either 40 residues downstream of the A-domain (B-domain) or the proximal C-terminus between S6 and the A-domain. Furthermore, the chimeras Q1ctQ3 and Q2ctQ3 showed > 10-fold increased current amplitudes compared to KCNQ1 or KCNQ2 alone and a strong depolarizing shift of voltage-dependent activation. The proximal part of the KCNQ3 C-terminus was necessary to produce these effects. Our results indicate that specific parts of the C-terminus enable the interaction between KCNQ2 and KCNQ3 channels and that different parts of the KCNQ3 C-terminus are important for regulating current amplitude.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Electrophysiology
  • Female
  • Humans
  • Ion Channel Gating / physiology
  • KCNQ2 Potassium Channel
  • KCNQ3 Potassium Channel
  • Membrane Potentials / physiology
  • Molecular Sequence Data
  • Oocytes / metabolism
  • Patch-Clamp Techniques
  • Potassium Channels / biosynthesis
  • Potassium Channels / genetics
  • Potassium Channels / physiology*
  • Potassium Channels, Voltage-Gated
  • RNA, Messenger / biosynthesis
  • Recombinant Fusion Proteins / metabolism
  • Xenopus laevis


  • KCNQ2 Potassium Channel
  • KCNQ2 protein, human
  • KCNQ3 Potassium Channel
  • KCNQ3 protein, human
  • Potassium Channels
  • Potassium Channels, Voltage-Gated
  • RNA, Messenger
  • Recombinant Fusion Proteins