The synaptophysin/synaptobrevin complex dissociates independently of neuroexocytosis

Clemens Reisinger, Sowmya V. Yelamanchili, Britta Hinz, Diana Mitter, Anja Becher, Hans Bigalke, Gudrun Ahnert-Hilger

Research output: Contribution to journalArticle

30 Scopus citations

Abstract

Synaptophysin is one of the most abundant membrane proteins of small synaptic vesicles. In mature nerve terminals it forms a complex with the vesicular membrane protein synaptobrevin, which appears to modulate synaptobrevin's interaction with the plasma membrane-associated proteins syntaxin and SNAP25 to form the SNARE complex as a prerequisite for membrane fusion. Here we show that synaptobrevin is preferentially cleaved by tetanus toxin while bound to synaptophysin or when existing as a homodimer. The synaptophysin/synaptobrevin complex is, however, not affected when neuronal secretion is blocked by botulinum A toxin which cleaves SNAP25. Excessive stimulation with α-latrotoxin or Ca2+-ionophores dissociates the synaptophysin/synaptobrevin complex and increases the interaction of the other SNARE proteins. The stimulation-induced dissociation of the synaptophysin/synaptobrevin complex is not inhibited by pre-incubating neurones with botulinum A toxin, but depends on extracellular calcium. However, the synaptophysin/synaptobrevin complex cannot be directly dissociated by calcium alone or in combination with magnesium. The dissociation of synaptobrevin from synaptophysin appears to precede its interaction with the other SNARE proteins and does not depend on the final fusion event. This finding further supports the modulatory role the synaptophysin/synaptobrevin complex may play in mature neurones.

Original languageEnglish (US)
Pages (from-to)1-8
Number of pages8
JournalJournal of Neurochemistry
Volume90
Issue number1
DOIs
StatePublished - Jul 2004

Keywords

  • Clostridial neurotoxins
  • Neuronal stimulation
  • SNARE complex
  • Synaptobrevin
  • Synaptophysin
  • Syp/Syb-complex

ASJC Scopus subject areas

  • Biochemistry
  • Cellular and Molecular Neuroscience

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