Synaptobrevin 2 (Syb2), syntaxin (Sx1A), and SNAP-25, generate a force to induce fusion pore formation. The v-SNARE, Syb2, is anchored to the vesicle membrane by a single transmembrane domain. Here we show that 2 tryptophans (W89/W90) located in the juxtamembrane domain of Syb2, which stabilize the transmembrane (TM) domain position, control the ratio of spontaneous vs. stimulated membrane fusion events in chromaffin cells. Changing the 2 hydrophobic tryptophans to neutral alanines promotes spontaneous membrane fusion, faster transmitter release kinetics and complete release from individual vesicles. The results indicate that the two tryptophans act as a fusion clamp making fusion stimulus-dependent. © 2012 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.
Fang, Q., Zhao, Y., & Lindau, M. (2013). Juxtamembrane tryptophans of synaptobrevin 2 control the process of membrane fusion. FEBS Letters, 587(1), 67–72. https://doi.org/10.1016/j.febslet.2012.11.002