Novel genetically encoded fluorescent probes enable real-time detection of potassium in vitro and in vivo

Nat Commun. 2017 Nov 10;8(1):1422. doi: 10.1038/s41467-017-01615-z.


Changes in intra- and extracellular potassium ion (K+) concentrations control many important cellular processes and related biological functions. However, our current understanding of the spatiotemporal patterns of physiological and pathological K+ changes is severely limited by the lack of practicable detection methods. We developed K+-sensitive genetically encoded, Förster resonance energy transfer-(FRET) based probes, called GEPIIs, which enable quantitative real-time imaging of K+ dynamics. GEPIIs as purified biosensors are suitable to directly and precisely quantify K+ levels in different body fluids and cell growth media. GEPIIs expressed in cells enable time-lapse and real-time recordings of global and local intracellular K+ signals. Hitherto unknown Ca2+-triggered, organelle-specific K+ changes were detected in pancreatic beta cells. Recombinant GEPIIs also enabled visualization of extracellular K+ fluctuations in vivo with 2-photon microscopy. Therefore, GEPIIs are relevant for diverse K+ assays and open new avenues for live-cell K+ imaging.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biosensing Techniques / methods*
  • Computer Systems
  • Extracellular Fluid / metabolism
  • Fluorescence Resonance Energy Transfer
  • Fluorescent Dyes*
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • HeLa Cells
  • Humans
  • In Vitro Techniques
  • Intracellular Fluid / metabolism
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Microscopy, Fluorescence, Multiphoton
  • Potassium / blood
  • Potassium / metabolism*
  • Potassium / urine


  • Cyan Fluorescent Protein
  • Fluorescent Dyes
  • Green Fluorescent Proteins
  • Potassium