Ratio of fusion events in the first second (5 acquisition frames) after Ca2+ or Mg2+ arrival to all fusion events (referred to as synchronization). ISV-SM vesicle association is normalized to the total number of available SM vesicles (“total ROI”). All fusion data, both Ca2+-dependent and Ca2+-independent, are normalized to the total number of ISV-SM vesicle pairs. Data are presented as mean ± SEM for association, fusion during association, and dissociation measurements for several replicates (Tables S1 and S2). For all bar graphs, a one-way ANOVA with post hoc Tukey-Kramer analysis was performed;*p < 0.05,**p < 0.005; n.s., not significant. For all cumulative probability histograms, a KS test was performed for all pairwise comparisons.
