Photoswitchable cyan fluorescent protein as a FRET donor

Microsc Res Tech. 2006 Mar;69(3):207-9. doi: 10.1002/jemt.20278.


Among a variety of fluorescent proteins available today, there is a lack of suitable markers with excitation/emission in the violet/blue part of visible spectrum. Recently, we reported on photoswitchable cyan fluorescent protein (PS-CFP), which represents monomeric high-contrasting photactivatable label for in vivo protein movement tracking. However, PS-CFP demands high intensity of light for the photoswitching. Therefore it can be employed as a common fluorescent tag at conventional light intensities, which cause negligible or zero photoactivation. High pH stability and unique positioning of excitation/emission peaks make it a worthy supplement to the existing palette of fluorescent proteins. Here we use PS-CFP fusion with a yellow fluorescent protein phiYFP to show that PS-CFP is a promising donor partner for the fluorescence resonance energy transfer (FRET). A remarkable phenomenon is that PS-CFP donor fluorescence turned to be essentially stable with and without FRET, while acceptor emission demonstrated record dynamic range of up to 7.8-fold. This makes the FRET pair presented a useful tool for the single color high throughput screenings. Here we also propose ways for further PS-CFP enhancing, aiming to develop bright cyan fluorescent protein with unique spectral characteristics.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / chemistry
  • Escherichia coli Proteins / chemistry
  • Fluorescence Resonance Energy Transfer / methods*
  • Green Fluorescent Proteins / radiation effects*
  • Light
  • Luminescent Proteins / chemistry
  • Recombinant Fusion Proteins / chemistry


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