A genetically targetable fluorescent probe of channel gating with rapid kinetics

Biophys J. 2002 Jan;82(1 Pt 1):509-16. doi: 10.1016/S0006-3495(02)75415-5.


We have developed a genetically targetable, optical channel-gating reporter that converts rapid membrane potential changes into changes in fluorescence intensity. We have named this construct SPARC (sodium channel protein-based activity reporting construct). Green fluorescent protein was inserted into an intracellular loop of a reversibly nonconducting form of the rat mu I skeletal muscle voltage-gated sodium channel. Rapid changes of the membrane potential modulate the fluorescence of the inserted green fluorescent protein. This change in fluorescence can faithfully report depolarizing pulses as short as 2 ms. The fluorescence signal does not inactivate during extended depolarizations. Several features of the probe's response properties indicate that it likely reports gating charge movement of a single domain of rat mu I skeletal muscle. This probe provides a new approach for studying rapid channel movements and may possibly act as a fluorescent activity reporter in excitable cells.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Fluorescent Dyes
  • Genes, Reporter*
  • Green Fluorescent Proteins
  • Ion Channel Gating / genetics
  • Ion Channel Gating / physiology*
  • Kinetics
  • Luminescent Proteins / analysis
  • Luminescent Proteins / genetics*
  • Membrane Potentials / physiology
  • Muscle, Skeletal / physiology*
  • Rats
  • Sodium Channels / physiology*
  • Transcription, Genetic


  • Fluorescent Dyes
  • Luminescent Proteins
  • Sodium Channels
  • Green Fluorescent Proteins