TABLE 2.

The molecular environment reported by di-4-ANEPPS is comparable in living cell membranes and model systems containing the same major sterol in a similar fraction.

Sterol	System	α1	τ1 (ns)	α2	τ2 (ns)	$\overline{\mathrm{\tau }}$ (ns)	<τ> (ns)
Erg	S. cerevisiae wt PM	0.40	1.50	0.60	2.95	2.37	2.58
	POPC/Erg (7:3)	0.41	1.53	0.59	2.77	2.26	2.42
	# DPPC/Erg (7:3)	0.50	1.50	0.50	3.90	2.70	3.24
Zym	S. cerevisiae erg6Δ PM	0.60	1.79	0.40	3.60	2.47	2.76
	DPPC/Zym (9:1)	0.65	1.70	0.35	3.51	2.33	2.64
	DPPC/Zym (8:2)	0.50	2.21	0.50	3.86	3.03	3.25
	POPC/Zym (9:1)	0.47	1.90	0.43	3.05	2.32	2.55
	POPC/Zym (8:2)	0.46	2.02	0.54	3.45	2.81	2.98
Chol	CHO-K1 PM	0.27	2.39	0.73	4.65	4.04	4.27
	CHO-K1 IM	0.41	1.99	0.59	4.27	3.35	3.72
	# DPPC/Chol (7:3)	0.23	2.09	0.77	4.50	4.01	4.22
	# PSM/Chol (7:3)	0.24	1.75	0.76	4.74	4.03	4.43
	# POPC/Chol (6:4)	0.43	2.02	0.57	3.57	2.92	3.12

Fluorescence intensity decay parameters of di-4-ANEPPS incorporated in yeast (S. cerevisiae) and mammalian (CHO-K1) cells, and in LUVs of different compositions containing Chol, Erg or Zym, at 24°C. The fluorescence intensity decays measured both in cells by FLIM (30–100 cells in three independent experiments) and in LUVs suspensions by fluorescence spectroscopy (at least three independent experiments) were described by the sum of two exponentials, with amplitudes α₁ and α₂ and lifetimes τ₁ and τ₂. $\overline{\mathit{\text{τ}}}$ is the amplitude-weighted average fluorescence lifetime and <τ> is the intensity-weighted mean fluorescence lifetime (Eqs. 1–3). ^#Values from Bastos et al. (2012).