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Dissecting docking and tethering of secretory vesicles at the target membrane
Author(s) -
Toonen Ruud F,
Kochubey Olexiy,
de Wit Heidi,
GulyasKovacs Attila,
Konijnenburg Bas,
Sørensen Jakob B,
Klingauf Jurgen,
Verhage Matthijs
Publication year - 2006
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7601256
Subject(s) - library science , humanities , computer science , philosophy
Secretory vesicles dock at their target in preparation for fusion. Using single‐vesicle total internal reflection fluorescence microscopy in chromaffin cells, we show that most approaching vesicles dock only transiently, but that some are captured by at least two different tethering modes, weak and strong. Both vesicle delivery and tethering depend on Munc18‐1, a known docking factor. By decreasing the amount of cortical actin by Latrunculin A application, morphological docking can be restored artificially in docking‐deficient munc18‐1 null cells, but neither strong tethering nor fusion, demonstrating that morphological docking is not sufficient for secretion. Deletion of the t‐SNARE and Munc18‐1 binding partner syntaxin, but not the v‐SNARE synaptobrevin/VAMP, also reduces strong tethering and fusion. We conclude that docking vesicles either undock immediately or are captured by minimal tethering machinery and converted in a munc18‐1/syntaxin‐dependent, strongly tethered, fusion‐competent state.