Munc18-1 promotes large dense-core vesicle docking. |
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| Authors: | T Voets R F Toonen E C Brian H de Wit T Moser J Rettig T C Südhof E Neher M Verhage |
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| Affiliation: | Department of Membrane Biophysics, Max-Planck-Institute for Biophysical Chemistry, Am Fassberg 11, 37077, G?ttingen, Germany. thomas.voets@med.kuleven.ac.be |
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| Abstract: | ![]()
Secretory vesicles dock at the plasma membrane before Ca(2+) triggers their exocytosis. Exocytosis requires the assembly of SNARE complexes formed by the vesicle protein Synaptobrevin and the membrane proteins Syntaxin-1 and SNAP-25. We analyzed the role of Munc18-1, a cytosolic binding partner of Syntaxin-1, in large dense-core vesicle (LDCV) secretion. Calcium-dependent LDCV exocytosis was reduced 10-fold in mouse chromaffin cells lacking Munc18-1, but the kinetic properties of the remaining release, including single fusion events, were not different from controls. Concomitantly, mutant cells displayed a 10-fold reduction in morphologically docked LDCVs. Moreover, acute overexpression of Munc18-1 in bovine chromaffin cells increased the amount of releasable vesicles and accelerated vesicle supply. We conclude that Munc18-1 functions upstream of SNARE complex formation and promotes LDCV docking. |
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