High-precision FLIM-FRET in fixed and living cells reveals heterogeneity in a simple CFP-YFP fusion protein

Biophys Chem. 2007 May;127(3):155-64. doi: 10.1016/j.bpc.2007.01.008. Epub 2007 Feb 1.


We have used widefield photon-counting FLIM to study FRET in fixed and living cells using control FRET pairs. We have studied fixed mammalian cells expressing either cyan fluorescent protein (CFP) or a fusion of CFP and yellow fluorescent protein (YFP), and living fungal cells expressing either Cerulean or a Cerulean-Venus fusion protein. We have found the fluorescence behaviour to be essentially identical in the mammalian and fungal cells. Importantly, the high-precision FLIM data is able to reproducibly resolve multiple fluorescence decays, thereby revealing new information about the fraction of the protein population that undergoes FRET and reducing error in the measurement of donor-acceptor distances. Our results for this simple control system indicate that the in vivo FLIM-FRET studies of more complex protein-protein interactions would benefit greatly from such quantitative measurements.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • COS Cells
  • Chlorocebus aethiops
  • Fluorescence Resonance Energy Transfer*
  • Green Fluorescent Proteins / chemistry*
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Luminescent Proteins / chemistry*
  • Luminescent Proteins / genetics
  • Luminescent Proteins / metabolism
  • Microscopy, Fluorescence / methods*
  • Photobleaching*
  • Recombinant Fusion Proteins / chemistry*
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism


  • Bacterial Proteins
  • Cyan Fluorescent Protein
  • Luminescent Proteins
  • Recombinant Fusion Proteins
  • yellow fluorescent protein, Bacteria
  • Green Fluorescent Proteins