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Updated: Dec 14, 2025

Analysis of SNARE-mediated Membrane Fusion Using an Enzymatic Cell Fusion Assay
09:19

Analysis of SNARE-mediated Membrane Fusion Using an Enzymatic Cell Fusion Assay

Published on: October 19, 2012

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Complexin Suppresses Spontaneous Exocytosis by Capturing the Membrane-Proximal Regions of VAMP2 and SNAP25

Jörg Malsam1, Simon Bärfuss1, Thorsten Trimbuch2

  • 1Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany.

Cell Reports
|July 23, 2020
PubMed

Insights

Complexin

Area of Science:

  • Neuroscience
  • Molecular Biology
  • Cell Biology

Background:

  • Complexin is a neuronal protein crucial for regulating neurotransmitter release.
  • It possesses both clamping and facilitatory functions.
  • The SNARE complex mediates intracellular membrane fusion.

Purpose of the Study:

  • To elucidate the clamping mechanism of complexin.
  • To understand how complexin regulates SNARE complex assembly.
  • To investigate the role of the complexin accessory helix in synaptic release.

Main Methods:

  • Reconstituted fusion assay.
  • Site- and stage-specific photo-cross-linking.
  • Analysis of complexin interface mutants in living neurons.

Main Results:

  • The complexin accessory helix arrests SNARE complex assembly by binding to SNAP25 and VAMP2.
  • This interaction occurs at the membrane-proximal C-terminal ends prior to fusion.
  • Mutations in the complexin interface enhance spontaneous neurotransmitter release.

Conclusions:

  • The complexin accessory helix acts as a clamp, suppressing SNARE complex zippering.
  • This suppression is achieved by restraining VAMP2 and SNAP25.
  • Complexin plays a critical role in tuning synaptic release probability.
Keywords:
SNAREcomplexincross-linkingmembrane fusionneurotransmissionsynaptotagminsyntaxin

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