Table 2.

γ-corrected smFRET efficiencies between fluorescent labels attached to the ternary SNARE complex (label pairs SFC1 and SFC2 as defined in Figure 2B) obtained from smFRET measurements in the presence and absence of 1 μM full-length wildtype complexin-1 (Cpx [1-134]). Mean γ-factors (Table 2—source data 1) were used to correct the smFRET efficiency histograms shown in Figure 4A–B using Equation (4) as described in the Materials and methods. The FRET efficiencies shown in the table are the peak positions of one or two Gaussian functions that were fit to the γ-corrected smFRET efficiency histograms, and the error bounds are standard deviations of the peak positions. As explained in the text, the population of the low FRET efficiency state in the presence of Cpx likely corresponds to the cis conformation of bound complexin-1, whereas the population of the high FRET efficiency state likely corresponds to the trans conformation of bound complexin-1 or SNARE complex alone. For comparison, FRET efficiencies were calculated from the crystal structure of the ternary SNARE complex (PDB ID: 1SFC, see Materials and methods for the calculation of FRET efficiencies from the crystal structures).

DOI: http://dx.doi.org/10.7554/eLife.16886.012

	γ-corrected smFRET efficiency - Cpx	γ-corrected smFRET efficiency +Cpx	FRET efficiency calculated from the crystal structure (PDB ID: 1SFC)
SFC1	0.85 ± 0.17	0.27 ± 0.11 0.85 ± 0.14	0.98
SFC2	0.90 ± 0.18	0.31 ± 0.13 0.86 ± 0.12	0.98