Cloning and functional expression of rKCNQ2 K(+) channel from rat brain

Brain Res Mol Brain Res. 2000 Sep 15;80(2):269-78. doi: 10.1016/s0169-328x(00)00146-7.


By homologue cloning, we have isolated a cDNA encoding a voltage-gated K(+) channel, rKCNQ2, from a rat brain cDNA library using RACE. The open reading frame of the translated protein comprises 852 amino acids with 6 transmembrane segments and a pore motif between S5 and S6. rKCNQ2 shares 96% amino acid identity with human KCNQ2 in which mutations cause a form of epilepsy known as benign familial neonatal convulsions (BFNC). Northern blotting with a rKCNQ2-specific probe revealed a robust single band of 8.6-kb transcript expressed in brain not in other tissues. Functional expression of rKCNQ2 in an HEK 293 cell line by whole-cell current recording and in Xenopus oocytes by two-electrode voltage clamp showed outward K(+) selective currents that displayed delayed rectifier-type kinetics. The G-V curve, fitted with a Boltzmann function, showed voltage dependence of activation with a threshold of activation approximately -60 mV. The rKCNQ2 currents were sensitive to TEA block with a Ki of 0.1 mM. In addition, rKCNQ2 currents were down-regulated upon exposure of cells to either a broad-spectrum tyrosine kinase inhibitor genistein or a Src-like tyrosine kinase inhibitor herbimycin A. Our findings add a rodent member to the KCNQ channel subfamily, providing new information of the channel modulation, and will facilitate generation of rodent models of epilepsy.

MeSH terms

  • Animals
  • Benzoquinones
  • Brain Chemistry / physiology*
  • Cells, Cultured
  • Cloning, Molecular
  • Enzyme Inhibitors / pharmacology
  • Epilepsy / genetics
  • Epilepsy / physiopathology
  • Gene Expression / physiology
  • Genistein / pharmacology
  • Humans
  • KCNQ2 Potassium Channel
  • Kidney / cytology
  • Lactams, Macrocyclic
  • Membrane Potentials / physiology
  • Molecular Sequence Data
  • Oocytes / physiology
  • Patch-Clamp Techniques
  • Phosphorylation
  • Potassium Channel Blockers
  • Potassium Channels / genetics
  • Potassium Channels, Voltage-Gated
  • Protein-Tyrosine Kinases / antagonists & inhibitors
  • Protein-Tyrosine Kinases / metabolism
  • Quinones / pharmacology
  • RNA, Messenger / analysis
  • Rats
  • Rifabutin / analogs & derivatives
  • Sequence Homology, Amino Acid
  • Tetraethylammonium / pharmacology
  • Tyrosine / metabolism
  • Xenopus


  • Benzoquinones
  • Enzyme Inhibitors
  • KCNQ2 Potassium Channel
  • KCNQ2 protein, human
  • Kcnq2 protein, rat
  • Lactams, Macrocyclic
  • Potassium Channel Blockers
  • Potassium Channels
  • Potassium Channels, Voltage-Gated
  • Quinones
  • RNA, Messenger
  • Rifabutin
  • Tyrosine
  • Tetraethylammonium
  • herbimycin
  • Genistein
  • Protein-Tyrosine Kinases