Third generation GFP biosensors for real time readout of pH and redox potential in living cells

S. James Remington, George T. Hanson, Mark Canon, Robert Aggeler, Devin Oglesbe, Roderick A. Capaldi, Roger Y. Tsien

Research output: Contribution to journalConference articlepeer-review

4 Scopus citations


Green fluorescent protein variants have been developed that report real-time change in pH and redox potential in living cells. The variants involve cystcine substitutions near the chromophore, which greatly alter the sensitivity of the protein to changes in its environment Measurements can be made on single living cells in the fluorescence microscope or in cell suspension with an ordinary fluorimeter. The indicators are ratiometric by emission and/or excitation, which means that measurements at two different wavelengths are sufficient to determine both the quantity being measured and the indicator GFP concentration. The photophysics of a novel blue/green dual emission GFP variant will be presented. The design principles, crystal structures and ultrafast spectroscopic analysis of probe response will be discussed in terms of atomic models involving excited state proton transfer. Some applications in living cells will be presented.

Original languageEnglish (US)
Pages (from-to)1-12
Number of pages12
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - Nov 16 2004
EventGenetically Engineered and Optical Probes for Biomedical Applications II - San Jose, CA, United States
Duration: Jan 24 2004Jan 27 2004


  • Biosensors
  • Fluorescent probes
  • Protein crystallography
  • Ratiometric indicators
  • Redox potential
  • pH sensors

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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