Single secretory granules of live cells recruit syntaxin-1 and synaptosomal associated protein 25 (SNAP-25) in large copy numbers

M. K. Knowles, S. Barg, L. Wan, M. Midorikawa, X. Chen, Wolfhard Almers

Research output: Contribution to journalArticle

70 Scopus citations

Abstract

Before secretory vesicles undergo exocytosis, they must recruit the proteins syntaxin-1 and synaptosomal associated protein 25 (SNAP-25) in the plasma membrane. GFP-labeled versions of both proteins cluster at siteswhere secretory granules have docked. Single-particle tracking shows that minority populations of both molecules are strongly hindered in their mobility, consistent with their confinement in nanodomains. We measured the fluorescence of granuleassociated clusters, the fluorescence of single molecules, and the numbers of unlabeled syntaxin-1 and SNAP-25 molecules per cell. There was a more than 10-fold excess of SNAP-25 over syntaxin-1. Fifty to seventy copies each of syntaxin-1 and SNAP-25 molecules were associated with a single docked granule,manymore than have been reported to be required for fusion.

Original languageEnglish (US)
Pages (from-to)20810-20815
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume107
Issue number48
DOIs
StatePublished - Nov 30 2010

Keywords

  • Location-guided averaging
  • Nanodomains
  • Single molecules
  • Single particle tracking
  • Total internal reflection fluorescence

ASJC Scopus subject areas

  • General

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