TABLE 1.

Summary of FRET measurements on the EGFP-mRFP1 fusion protein in cells

	Lifetime	Dual-color PCH	Spectra
FRET efficiency	0.52 ± 0.02	0.54 ± 0.05	0.52
Fraction of EGFP-mRFP1	0.33 ± 0.07	0.40 ± 0.05	0.35

All three measurements agree within errors on the FRET efficiency of the fusion protein and on the fraction of EGFP-mRFP1 with fluorescent mRFP1; ∼60% of the fusion proteins did not show fluorescence of mRFP1.