Figure 2.
Munc13 and Munc18 protect SNARE complexes from disassembly by NSF. A & B. Inappropriate SNARE complexes (e.g. two Syntaxins with one SNAP25 or VAMP2 assembling in an antiparallel orientation with syntaxin 1) are rapidly disassembled by NSF (pink) and SNAP (brown). Note that SNAP25 has been omitted for simplicity. C. SNARE complexes assembled while bound to Munc13–1 (orange) and Munc18–1 (green) are protected from NSF and are correctly oriented. D. Vesicle fusion proceeds efficiently upon calcium elevation when all SNARE complexes have assembled appropriately as guided by Munc13–1 and Munc18–1.