Tyrosine phosphorylation of Munc18-1 inhibits synaptic transmission by preventing SNARE assembly

EMBO J. 2018 Jan 17;37(2):300-320. doi: 10.15252/embj.201796484. Epub 2017 Nov 17.


Tyrosine kinases are important regulators of synaptic strength. Here, we describe a key component of the synaptic vesicle release machinery, Munc18-1, as a phosphorylation target for neuronal Src family kinases (SFKs). Phosphomimetic Y473D mutation of a SFK phosphorylation site previously identified by brain phospho-proteomics abolished the stimulatory effect of Munc18-1 on SNARE complex formation ("SNARE-templating") and membrane fusion in vitro Furthermore, priming but not docking of synaptic vesicles was disrupted in hippocampal munc18-1-null neurons expressing Munc18-1Y473D Synaptic transmission was temporarily restored by high-frequency stimulation, as well as by a Munc18-1 mutation that results in helix 12 extension, a critical conformational step in vesicle priming. On the other hand, expression of non-phosphorylatable Munc18-1 supported normal synaptic transmission. We propose that SFK-dependent Munc18-1 phosphorylation may constitute a potent, previously unknown mechanism to shut down synaptic transmission, via direct occlusion of a Synaptobrevin/VAMP2 binding groove and subsequent hindrance of conformational changes in domain 3a responsible for vesicle priming. This would strongly interfere with the essential post-docking SNARE-templating role of Munc18-1, resulting in a largely abolished pool of releasable synaptic vesicles.

Keywords: SNARE; Munc18‐1; Src; priming; synaptic transmission.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Mice
  • Mice, Knockout
  • Munc18 Proteins / genetics
  • Munc18 Proteins / metabolism*
  • Mutation
  • Phosphorylation / physiology
  • Protein Structure, Secondary
  • R-SNARE Proteins / genetics
  • R-SNARE Proteins / metabolism
  • SNARE Proteins / genetics
  • SNARE Proteins / metabolism*
  • Synaptic Transmission / physiology*
  • Synaptic Vesicles / genetics
  • Synaptic Vesicles / metabolism*
  • Vesicle-Associated Membrane Protein 2 / genetics
  • Vesicle-Associated Membrane Protein 2 / metabolism
  • src-Family Kinases / genetics
  • src-Family Kinases / metabolism*


  • Munc18 Proteins
  • R-SNARE Proteins
  • SNARE Proteins
  • Stxbp1 protein, mouse
  • Vesicle-Associated Membrane Protein 2
  • vesicle-associated membrane protein 2, mouse
  • src-Family Kinases