title: A dual mechanism controlling the localization and function of exocytic v-SNAREs.
abstract: SNARE [soluble NSF (N-ethylmaleimide-sensitive factor) attachment protein receptor] proteins are essential for membrane fusion but their regulation is not yet fully understood. We have previously shown that the amino-terminal Longin domain of the v-SNARE TI-VAMP (tetanus neurotoxin-insensitive vesicle-associated membrane protein)/VAMP7 plays an inhibitory role in neurite outgrowth. The goal of this study was to investigate the regulation of TI-VAMP as a model of v-SNARE regulation. We show here that the Longin domain (LD) plays a dual role. First, it negatively regulates the ability of TI-VAMP and of a Longin/Synaptobrevin chimera to participate in SNARE complexes. Second, it interacts with the adaptor complex AP-3 and this interaction targets TI-VAMP to late endosomes. Accordingly, in mocha cells lacking AP-3 delta, TI-VAMP is retained in an early endosomal compartment. Furthermore, TI-VAMPc, an isoform of TI-VAMP lacking part of the LD, does not interact with AP-3, and therefore is not targeted to late endosomes; however, this shorter LD still inhibits SNARE-complex formation. These findings support a mechanism controlling both localization and function of TI-VAMP through the LD and clathrin adaptors. Moreover, they point to the amino-terminal domains of SNARE proteins as multifunctional modules responsible for the fine tuning of SNARE function.
authors.affiliation: Membrane Traffic and Neuronal Plasticity, Institut National de la Santé et de la Recherche Médicale U536, Institut du Fer-à-Moulin, 75005 Paris, France.
authors.forename: Sonia
authors.initials: S
authors.lastname: Martinez-Arca
authors.forename: Rachel
authors.initials: R
authors.lastname: Rudge
authors.forename: Marcella
authors.initials: M
authors.lastname: Vacca
authors.forename: Graça
authors.initials: G
authors.lastname: Raposo
authors.forename: Jacques
authors.initials: J
authors.lastname: Camonis
authors.forename: Véronique
authors.initials: V
authors.lastname: Proux-Gillardeaux
authors.forename: Laurent
authors.initials: L
authors.lastname: Daviet
authors.forename: Etienne
authors.initials: E
authors.lastname: Formstecher
authors.forename: Alexandre
authors.initials: A
authors.lastname: Hamburger
authors.forename: Francesco
authors.initials: F
authors.lastname: Filippini
authors.forename: Maurizio
authors.initials: M
authors.lastname: D'Esposito
authors.forename: Thierry
authors.initials: T
authors.lastname: Galli
mesh_terms: D033963:Adaptor Protein Complex 3; D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism; D004285:Dogs; D005089:Exocytosis; D006367:HeLa Cells; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism; D050683:R-SNARE Proteins; D050600:SNARE Proteins; D013347:Subcellular Fractions / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D033921:Vesicular Transport Proteins
chemical_list: D033963:Adaptor Protein Complex 3; D004268:DNA-Binding Proteins; D008565:Membrane Proteins; D010446:Peptide Fragments; D050683:R-SNARE Proteins; D050600:SNARE Proteins; D014157:Transcription Factors; C121241:VAMP7 protein, human; D033921:Vesicular Transport Proteins