TABLE 2.
Lifetimes and FRET efficiencies estimated by means of FLIM for complexes at the plasma membrane
Fluorescence was monitored from 52 cells in which eGFP-M2 and eYFP-M2 were localized predominantly at the plasma membrane. The traces from binned pixels were analyzed in terms of two or three exponentials (Equation 22), and the resulting distribution of lifetimes from each cell was analyzed as a sum of gaussians (Equation 23). Lifetimes from two exponentials were described by two gaussians throughout (line A) or by either two or three gaussians (line B), as determined by the F-statistic. Lifetimes from three exponentials were described by three gaussians (line C). The estimates of τ0,j from individual cells were averaged to obtain the means (±S.E.) listed in the table, where τ0,1, τ0,2, and τ0,3 correspond to τDA, τD, and τA, respectively. The number of traces is shown in parentheses. Efficiencies were calculated from τDA and τD for each cell (Equation 24), and the individual values were averaged to obtain the means (±S.E.) listed in the table.
| q (Equation 22) | q (Equation 23) | Lifetime |
Efficiency (Equation 24) | |||
|---|---|---|---|---|---|---|
| τ0,1 (τDA) | τ0,2 (τD) | τ0,3 (τA) | ||||
| ns | ns | ns | ||||
| A | 2 | 2 (52) | 2.01 ± 0.04 (52) | 2.55 ± 0.03 (52) | 0.21 ± 0.02 | |
| B | 2 | 2 (14) | 1.94 ± 0.03 (52) | 2.41 ± 0.01 (52) | 2.83 ± 0.04 (38) | 0.20 ± 0.01 |
| 3 (38) | ||||||
| C | 3 | 3 (52) | 1.79 ± 0.04 (52) | 2.35 ± 0.02 (52) | 3.00 ± 0.09 (38) | 0.24 ± 0.02 |