Conical electron tomography of a chemical synapse: vesicles docked to the active zone are hemi-fused.

Journal Article (Journal Article)

We have used thin sectioning and conical electron tomography to determine the three-dimensional structure of synaptic vesicles that were associated (docked) at release sites of the presynaptic membrane, called active-zones. Vesicles docked at the active zone occupied a strategic location: they formed regions of contact with the plasma membrane on one side and with that of one or more vesicles located deeper within the presynaptic terminal on the other side. The region of contact with the active zone measured approximately 15 nm in diameter ( approximately 2% of the vesicle's surface) and contained a smaller approximately 6 nm region where the proximal leaflets merged (hemi-fused). Hemi-fusion was only observed on the side of vesicles in contact with the active zone; at the side of contact between neighboring vesicles, the membranes were not hemi-fused. Approximately three-fourths of the docked vesicles contained hemi-fused regions. Vesicles fully fused to the active zone (exhibiting pores that appeared as interruptions of a single membrane) were less frequently observed ( approximately 1 of 10 hemi-fused vesicles). In conclusion, our observations in cortical synapses strengthen the hypothesis that hemi-fusion is a stable intermediary that precedes full fusion and release.

Full Text

Duke Authors

Cited Authors

  • Zampighi, GA; Zampighi, LM; Fain, N; Lanzavecchia, S; Simon, SA; Wright, EM

Published Date

  • October 15, 2006

Published In

Volume / Issue

  • 91 / 8

Start / End Page

  • 2910 - 2918

PubMed ID

  • 16877508

Pubmed Central ID

  • PMC1578491

International Standard Serial Number (ISSN)

  • 0006-3495

Digital Object Identifier (DOI)

  • 10.1529/biophysj.106.084814


  • eng

Conference Location

  • United States