Fig. 6.

Epigallocatechin gallate inhibits insulin secretory SNARE‐dependent membrane fusion in the presence of Syt7 and Ca²⁺. (A) Illustrations of the liposome fusion procedures. The t‐SNARE liposomes containing syntaxin‐1 and SNAP‐25 were reconstituted using the lipid composition: 50% POPC, 20% POPE, 15% POPS, 10% cholesterol, 3% 1‐palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐phosphoinositol (POPI) and 2% phosphatidylinositol‐4,5‐bisphosphate (PIP2). The v‐SNARE liposomes containing VAMP2 and Syt7 were prepared using the lipid composition: 47% POPC, 20% POPE, 15% POPS, 10% cholesterol, 5% POPI, 1.5% rhodamine‐DPPE and 1.5% NBD‐DPPE. The v‐ and t‐SNARE liposomes were mixed with 10 μm EGCG in the presence of 0.2 mm EGTA and 100 mg·mL⁻¹ Ficoll 70. The samples were incubated at 37 °C for 20 min. Subsequently, 1 mm CaCl₂ (or 1 mm EGTA) was added, and the fusion reactions were monitored for 60 min. (B) Lipid mixing of the reconstituted fusion reactions. The fusion reactions were measured by a FRET‐based lipid mixing assay. (C) Initial lipid mixing rates of the liposome fusion reactions shown in (B). Data are presented as a percentage of fluorescence change per 10 min. Error bars indicate the SD. Data are presented as the mean ± SD (n = 3 independent replicates). P values were calculated using two‐way ANOVA with Tukey's multiple comparisons test. **P < 0.01; ****P < 0.0001.