Single action potentials and subthreshold electrical events imaged in neurons with a fluorescent protein voltage probe

Neuron. 2012 Sep 6;75(5):779-85. doi: 10.1016/j.neuron.2012.06.040.


Monitoring neuronal electrical activity using fluorescent protein-based voltage sensors has been limited by small response magnitudes and slow kinetics of existing probes. Here we report the development of a fluorescent protein voltage sensor, named ArcLight, and derivative probes that exhibit large changes in fluorescence intensity in response to voltage changes. ArcLight consists of the voltage-sensing domain of Ciona intestinalis voltage-sensitive phosphatase and super ecliptic pHluorin that carries the point mutation A227D. The fluorescence intensity of ArcLight A242 decreases by 35% in response to a 100 mV depolarization when measured in HEK293 cells, which is more than five times larger than the signals from previously reported fluorescent protein voltage sensors. We show that the combination of signal size and response speed of these new probes allows the reliable detection of single action potentials and excitatory potentials in individual neurons and dendrites.

Publication types

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

MeSH terms

  • Action Potentials / physiology*
  • Animals
  • Biosensing Techniques / methods
  • Ciona intestinalis
  • Fluorescent Dyes / chemical synthesis*
  • Green Fluorescent Proteins / chemistry*
  • HEK293 Cells
  • Humans
  • Luminescent Proteins / chemical synthesis*
  • Luminescent Proteins / genetics
  • Microscopy, Fluorescence / methods
  • Neurons / physiology*
  • Point Mutation / genetics
  • Recombinant Fusion Proteins / chemical synthesis*
  • Recombinant Fusion Proteins / genetics
  • Synaptic Potentials / physiology*
  • Voltage-Sensitive Dye Imaging / methods*


  • Arclight fusion protein
  • Fluorescent Dyes
  • Luminescent Proteins
  • PHluorin
  • Recombinant Fusion Proteins
  • enhanced green fluorescent protein
  • Green Fluorescent Proteins