(A) Titration of liposomes (2.2 nM liposomes composed of 30% PE/70% PC) against [FM1–43]. The dashed line represents the signal obtained from liposomes only, and the solid lines are liposomes plus the indicated [FM1–43]. (B–H) Fluorescence intensities, determined by integration of emission spectra of dye•liposome complexes (500–700 nm for FM1–84, FM1–43, SynaptoGreen C3, and FM2–10; 550–750 nm for FM4–64 and FM5–95; 500–650 nm for SGC5), are indicated by solid squares. Fluorescence intensities of samples that contained dyes but lacked liposomes are indicated by open squares. (I) Dye•liposome fluorescence intensities were corrected by subtracting the free dye signals; these data are plotted versus [dye]. (J) Ratio of fluorescence intensities of dyes with and without liposomes. Error bars are mean ± SE from three separate experiments.