Calcium-independent stimulation of membrane fusion and SNAREpin formation by synaptotagmin I

Lara K. Mahal, Sonia M. Sequeira, Jodi M. Gureasko, Thomas H. Söllner

Research output: Contribution to journalArticlepeer-review


Neurotransmitter release requires the direct coupling of the calcium sensor with the machinery for membrane fusion. SNARE proteins comprise the minimal fusion machinery, and synaptotagmin I, a synaptic vesicle protein, is the primary candidate for the main neuronal calcium sensor. To test the effect of synaptotagmin I on membrane fusion, we incorporated it into a SNARE-mediated liposome fusion assay. Synaptotagmin I dramatically stimulated membrane fusion by facilitating SNAREpin zippering. This stimulatory effect was topologically restricted to v-SNARE vesicles (containing VAMP 2) and only occurred in trans to t-SNARE vesicles (containing syntaxin 1A and SNAP-25). Interestingly, calcium did not affect the overall fusion reaction. These results indicate that synaptotagmin I can directly accelerate SNARE-mediated membrane fusion and raise the possibility that additional components might be required to ensure tight calcium coupling.

Original languageEnglish (US)
Pages (from-to)273-282
Number of pages10
JournalJournal of Cell Biology
Issue number2
StatePublished - Jul 22 2002


  • Calcium
  • Exocytosis
  • Fusion
  • Synaptotagmin

ASJC Scopus subject areas

  • Cell Biology


Dive into the research topics of 'Calcium-independent stimulation of membrane fusion and SNAREpin formation by synaptotagmin I'. Together they form a unique fingerprint.

Cite this