Strengths and weaknesses of recently engineered red fluorescent proteins evaluated in live cells using fluorescence correlation spectroscopy

Amanda P. Siegel, Michelle A. Baird, Michael W. Davidson, Richard N. Day

Research output: Contribution to journalArticle

18 Scopus citations


The scientific community is still looking for a bright, stable red fluorescent protein (FP) as functional as the current best derivatives of green fluorescent protein (GFP). The red FPs exploit the reduced background of cells imaged in the red region of the visible spectrum, but photophysical short comings have limited their use for some spectroscopic approaches. Introduced nearly a decade ago, mCherry remains the most often used red FP for fluorescence correlation spectroscopy (FCS) and other single molecule techniques, despite the advent of many newer red FPs. All red FPs suffer from complex photophysics involving reversible conversions to a dark state (flickering), a property that results in fairly low red FP quantum yields and potential interference with spectroscopic analyses including FCS. The current report describes assays developed to determine the best working conditions for, and to uncover the shortcoming of, four recently engineered red FPs for use in FCS and other diffusion and spectroscopic studies. All five red FPs assayed had potential shortcomings leading to the conclusion that the current best red FP for FCS is still mCherry. The assays developed here aim to enable the rapid evaluation of new red FPs and their smooth adaptation to live cell spectroscopic microscopy and nanoscopy.

Original languageEnglish (US)
Pages (from-to)20340-20358
Number of pages19
JournalInternational journal of molecular sciences
Issue number10
StatePublished - Oct 14 2013



  • Diffusion
  • Flickering
  • Fluorescent correlation spectroscopy (FCS)
  • Fluorescent protein
  • Intrinsic brightness

ASJC Scopus subject areas

  • Computer Science Applications
  • Molecular Biology
  • Catalysis
  • Inorganic Chemistry
  • Spectroscopy
  • Organic Chemistry
  • Physical and Theoretical Chemistry

Cite this