The t-SNARE syntaxin is sufficient for spontaneous fusion of synaptic vesicles to planar membranes |
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Authors: | Woodbury D J Rognlien K |
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Institution: | Department of Physiology, Wayne State University, School of Medicine, Detroit, MI 48201, USA. woodbury@med.wayne.edu |
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Abstract: | Vesicular trafficking and exocytosis are directed by the complementary interaction of membrane proteins that together form the SNARE complex. This complex is composed of proteins in the vesicle membrane (v-SNAREs) that intertwine with proteins of the target membrane (t-SNAREs). Here we show that modified synaptic vesicles (mSV), containing v-SNAREs, spontaneously fuse to planar membranes containing the t-SNARE, syntaxin 1A. Fusion was Ca(2+)-independent and did not occur with vesicles lacking v-SNAREs. Therefore, syntaxin alone forms a functional fusion complex with v-SNAREs. Our functional fusion assay uses synaptic vesicles that are modified, so each fusion event results in an observable transient current. The mSV do not fuse with protein-free membranes. Additionally, artificial vesicles lacking v-SNAREs do not fuse with membranes containing syntaxin. This technique can be adapted to measure fusion in other SNARE systems and should enable the identification of proteins critical to vesicle-membrane fusion. This will further our understanding of exocytosis and may improve targeting and delivery of therapeutic agents packaged in vesicles. |
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Keywords: | syntaxin 1A v‐SNARE SNAP‐25 nystatin/ergosterol fusion Torpedo californica planar lipid bilayer |
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