Complexin and Ca2+ stimulate SNARE-mediated membrane fusion

Tae Young Yoon, Xiaobing Lu, Jiajie Diao, Soo Min Lee, Taekjip Ha, Yeon Kyun Shin

Research output: Contribution to journalArticlepeer-review


Ca2+-triggered, synchronized synaptic vesicle fusion underlies interneuronal communication. Complexin is a major binding partner of the SNARE complex, the core fusion machinery at the presynapse. The physiological data on complexin, however, have been at odds with each other, making delineation of its molecular function difficult. Here we report direct observation of two-faceted functions of complexin using the single-vesicle fluorescence fusion assay and EPR. We show that complexin I has two opposing effects on trans-SNARE assembly: inhibition of SNARE complex formation and stabilization of assembled SNARE complexes. Of note, SNARE-mediated fusion is markedly stimulated by complexin, and it is further accelerated by two orders of magnitude in response to an externally applied Ca2+ wave. We suggest that SNARE complexes, complexins and phospholipids collectively form a complex substrate for Ca 2+ and Ca2+-sensing fusion effectors in neurotransmitter release.

Original languageEnglish (US)
Pages (from-to)707-713
Number of pages7
JournalNature Structural and Molecular Biology
Issue number7
StatePublished - Jul 2008
Externally publishedYes

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology


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