Control of fusion pore dynamics during exocytosis by Munc18

Science. 2001 Feb 2;291(5505):875-8. doi: 10.1126/science.291.5505.875.


Intracellular membrane fusion is mediated by the SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins. All vesicle transport steps also have an essential requirement for a member of the Sec1 protein family, including the neuronal Munc18-1 (also known as nSec1) in regulated exocytosis. Here, in adrenal chromaffin cells, we expressed a Munc18 mutant with reduced affinity for syntaxin, which specifically modified the kinetics of single-granule exocytotic release events, consistent with an acceleration of fusion pore expansion. Thus, Munc18 functions in a late stage in the fusion process, where its dissociation from syntaxin determines the kinetics of postfusion events.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Action Potentials
  • Adrenal Medulla / cytology
  • Animals
  • Antigens, Surface / metabolism
  • Catecholamines / metabolism
  • Cattle
  • Cells, Cultured
  • Chromaffin Cells / physiology*
  • Exocytosis*
  • Membrane Fusion*
  • Munc18 Proteins
  • Mutation
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism*
  • PC12 Cells
  • Phosphorylation
  • Rats
  • Secretory Vesicles / physiology*
  • Syntaxin 1
  • Transfection
  • Vesicular Transport Proteins*


  • Antigens, Surface
  • Catecholamines
  • Munc18 Proteins
  • Nerve Tissue Proteins
  • Stxbp1 protein, rat
  • Syntaxin 1
  • Vesicular Transport Proteins