Fig. 6.

SLP and Vc peptide activate SNARE-mediated membrane fusion through a similar mechanism. (A) Diagrams of the molecules added to the reconstituted fusion reaction: Vc peptide, Munc18-1–derived SLP, Munc18-1–derived SLP with an engineered transmembrane domain (TMD, from VAMP2), and the TolA helix with a VAMP2-derived TMD. The sequences of the chimeras are included in Materials and Methods. (B) Reconstituted SNARE-dependent fusion reactions containing 5 µM WT synaptic exocytic t-SNAREs, 1.5 µM WT VAMP2, 100 mg/mL Ficoll 70, and 5 μM of the indicated molecules. (C) Initial lipid-mixing rates of the reconstituted fusion reactions shown in B. (D) Reconstituted liposome fusion reactions were performed as described in B in the absence or presence of 5 μM Munc18-1. (E) Initial lipid-mixing rates of the reconstituted fusion reactions shown in D. Data in C and E are presented as the percentage of fluorescence change per 10 min. Error bars indicate SD.