Figure 2.

The N-terminal affinity of liposomes is augmented in the presence of PS. (A) Cartoon of the FRET analysis. Binding was tested using FRET between a peptide containing Trp (W) (donor) and liposomes labeled with dansyl-PE (acceptor). The initial spectrum of Trp was determined in the absence of liposomes (F₀) and the subsequent spectrum was recorded after liposome addition (F). (B) Fluorescence of Trp in the absence (black trace) or presence (red traces) of liposomes with 15% PS. A.U., absorbance units. FRET is presented as F₀/F at 355 nm. (C) Summary of FRET changes with different lipid compositions of the liposomes. FRET is presented as F₀/F at 355 nm. n = 3; ^∗∗p < 0.05, compared with PS-free liposome; error bar, ± SEM. (D) FRET (F₀/F) signals in the presence of PS and/or PIP₂. FRET (F₀/F) is represented as a function of the concentration of lipids. (E) Confocal images of cells expressing the PS probe Lact-C2-GFP and the β2e subunit tagged with mCherry. Scale bar, 5 μm. (F) Effects of a transfected PS probe on the inactivation of Ca_V2.2 currents with the β2e subunit. PS masking by Lact-C2 accelerates the inactivation of Ca_V2.2 currents. Currents were measured during a 500 ms test pulse to +10 mV. The current trace obtained with the β2e subunit and Lact-C2 is scaled to the peak amplitude of currents obtained with the β2e subunit only (control). (G) Summary of current inactivation by Lact-C2 expression (n = 4–5). ^∗p < 0.05, compared with control; error bar, ± SEM. To see this figure in color, go online.