title: SNARE complexes and neuroexocytosis: how many, how close?
abstract: Regulated secretion is an essential process in all eukaryotic cells. The release of molecules contained inside exocytic granules and synaptic vesicles is mediated by the assembly of a SNARE complex formed by the coil-coiling of three proteins: SNAP-25, syntaxin and VAMP/synaptobrevin. It seems that SNARE complexes assemble together in rosette-shaped super-complexes but there is controversy on the actual number (N) of copies of SNARE complexes that are necessary to mediate exocytosis. We discuss attempts to determine the value of N and suggest that N varies with the type of exocytic vesicles. In addition, we propose that the N value in neuroexocytosis can be estimated by the comparative use of different types of botulinum neurotoxins.
authors.affiliation: Dipartimento di Scienze Biomediche and Istituto CNR di Neuroscienze, Università di Padova, Viale G. Colombo n. 3, 35121 Padova, Italy. cesare.montecucco@unipd.it
authors.forename: Cesare
authors.initials: C
authors.lastname: Montecucco
authors.forename: Giampietro
authors.initials: G
authors.lastname: Schiavo
authors.forename: Sergio
authors.initials: S
authors.lastname: Pantano
mesh_terms: D000818:Animals; D001905:Botulinum Toxins / Q000378:metabolism / Q000633:toxicity; D005089:Exocytosis / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D008954:Models, Biological; D009474:Neurons / Q000502:physiology*; D050600:SNARE Proteins; D033921:Vesicular Transport Proteins / Q000378:metabolism*
chemical_list: D050600:SNARE Proteins; D033921:Vesicular Transport Proteins; D001905:Botulinum Toxins