Functional reconstitution of cell-free synthesized purified Kv channels

Biochim Biophys Acta Biomembr. 2017 Dec;1859(12):2373-2380. doi: 10.1016/j.bbamem.2017.09.002. Epub 2017 Sep 6.


The study of ion channel activity and the screening of possible inhibitor molecules require reliable methods for production of active channel proteins, their insertion into artificial membranes and for the measurement of their activity. Here we report on cell-free expression of soluble and active Kv1.1 and Kv1.3 channels and their efficient insertion into liposomes. Two complementary methods for the determination of the electrical activity of the proteoliposome-embedded channels were compared using Kv1.1 as a model system: (1) single channel recordings in droplet interface bilayers (DIB) and (2) measurement of the membrane voltage potential generated by a potassium ion diffusion potential using the voltage-sensitive fluorescent dye oxonol VI. Single channel recordings in DIBs proved unreliable because of the non-reproducible fusion of proteoliposomes with an artificial membrane. Therefore, the use of the optical indicator oxonol VI was adapted for 96 well microtiter plates using the ionophore valinomycin as a positive control. The activity of Kv1.1 and Kv1.3 channels was then monitored in the absence and presence of different venom toxins, demonstrating that fluorescent dyes can be used very efficiently when screening small molecules for their channel blocking activity.

Keywords: DIB; K(v) channels; Oxonol VI; Proteoliposomes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Elapid Venoms / pharmacology
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Fluorescent Dyes / chemistry
  • Gene Expression
  • Genetic Vectors / chemistry
  • Genetic Vectors / metabolism
  • Humans
  • Isoxazoles / chemistry
  • Kv1.1 Potassium Channel / genetics
  • Kv1.1 Potassium Channel / metabolism*
  • Kv1.3 Potassium Channel / genetics
  • Kv1.3 Potassium Channel / metabolism*
  • Membrane Potentials / drug effects*
  • Phosphatidylcholines / chemistry
  • Phosphatidylcholines / metabolism
  • Phosphatidylethanolamines / chemistry
  • Phosphatidylethanolamines / metabolism
  • Phosphatidylserines / chemistry
  • Phosphatidylserines / metabolism
  • Proteolipids / chemistry
  • Proteolipids / drug effects*
  • Proteolipids / metabolism
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Subcellular Fractions / metabolism
  • Valinomycin / pharmacology


  • Elapid Venoms
  • Fluorescent Dyes
  • Isoxazoles
  • Kv1.3 Potassium Channel
  • Phosphatidylcholines
  • Phosphatidylethanolamines
  • Phosphatidylserines
  • Proteolipids
  • Recombinant Proteins
  • proteoliposomes
  • Kv1.1 Potassium Channel
  • Valinomycin
  • dioleoyl phosphatidylethanolamine
  • 1,2-diphytanoylphosphatidylcholine
  • oxonol VI
  • 1,2-dioleoylphosphatidylserine
  • dendrotoxin
  • 1,2-oleoylphosphatidylcholine