title: v-SNAREs control exocytosis of vesicles from priming to fusion.
abstract: SNARE proteins (soluble NSF-attachment protein receptors) are thought to be central components of the exocytotic mechanism in neurosecretory cells, but their precise function remained unclear. Here, we show that each of the vesicle-associated SNARE proteins (v-SNARE) of a chromaffin granule, synaptobrevin II or cellubrevin, is sufficient to support Ca(2+)-dependent exocytosis and to establish a pool of primed, readily releasable vesicles. In the absence of both proteins, secretion is abolished, without affecting biogenesis or docking of granules indicating that v-SNAREs are absolutely required for granule exocytosis. We find that synaptobrevin II and cellubrevin differentially control the pool of readily releasable vesicles and show that the v-SNARE's amino terminus regulates the vesicle's primed state. We demonstrate that dynamics of fusion pore dilation are regulated by v-SNAREs, indicating their action throughout exocytosis from priming to fusion of vesicles.
authors.affiliation: Department of Physiology, University of Saarland, Homburg/Saar, Germany.
authors.forename: Maria
authors.initials: M
authors.lastname: Borisovska
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhao
authors.forename: Yaroslav
authors.initials: Y
authors.lastname: Tsytsyura
authors.forename: Nataliya
authors.initials: N
authors.lastname: Glyvuk
authors.forename: Shigeo
authors.initials: S
authors.lastname: Takamori
authors.forename: Ulf
authors.initials: U
authors.lastname: Matti
authors.forename: Jens
authors.initials: J
authors.lastname: Rettig
authors.forename: Thomas
authors.initials: T
authors.lastname: Südhof
authors.forename: Dieter
authors.initials: D
authors.lastname: Bruns
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000378:metabolism; D003594:Cytoplasmic Granules / Q000648:ultrastructure; D022162:Cytoplasmic Vesicles / Q000378:metabolism*; D005089:Exocytosis / Q000502:physiology*; D008561:Membrane Fusion / Q000502:physiology*; D008565:Membrane Proteins / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D050683:R-SNARE Proteins; D050600:SNARE Proteins; D013997:Time Factors; D051040:Vesicle-Associated Membrane Protein 3; D033921:Vesicular Transport Proteins / Q000172:deficiency / Q000378:metabolism*
chemical_list: D008565:Membrane Proteins; D050683:R-SNARE Proteins; D050600:SNARE Proteins; D051040:Vesicle-Associated Membrane Protein 3; D033921:Vesicular Transport Proteins; D002118:Calcium