title: Increased activity of the vesicular soluble N-ethylmaleimide-sensitive factor attachment protein receptor TI-VAMP/VAMP7 by tyrosine phosphorylation in the Longin domain.
abstract: Vesicular (v)- and target (t)-SNAREs play essential roles in intracellular membrane fusion through the formation of cytoplasmic α-helical bundles. Several v-SNAREs have a Longin N-terminal extension that, by promoting a closed conformation, plays an autoinhibitory function and decreases SNARE complex formation and membrane fusion efficiency. The molecular mechanism leading to Longin v-SNARE activation is largely unknown. Here we find that exocytosis mediated by the Longin v-SNARE TI-VAMP/VAMP7 is activated by tonic treatment with insulin and insulin-like growth factor-1 but not by depolarization and intracellular calcium rise. In search of a potential downstream mechanism, we found that TI-VAMP is phosphorylated in vitro by c-Src kinase on tyrosine 45 of the Longin domain. Accordingly, a mutation of tyrosine 45 into glutamate, but not phenylalanine, activates both t-SNARE binding and exocytosis. Activation of TI-VAMP-mediated exocytosis thus relies on tyrosine phosphorylation.
authors.affiliation: Institut Jacques Monod, UMR 7592, CNRS, Université Paris Diderot, Sorbonne Paris Cité, F-75013 Paris, France.
authors.forename: Andrea
authors.initials: A
authors.lastname: Burgo
authors.forename: Alessandra M
authors.initials: AM
authors.lastname: Casano
authors.forename: Aurelia
authors.initials: A
authors.lastname: Kuster
authors.forename: Stefan T
authors.initials: ST
authors.lastname: Arold
authors.forename: Guan
authors.initials: G
authors.lastname: Wang
authors.forename: Sébastien
authors.initials: S
authors.lastname: Nola
authors.forename: Agathe
authors.initials: A
authors.lastname: Verraes
authors.forename: Florent
authors.initials: F
authors.lastname: Dingli
authors.forename: Damarys
authors.initials: D
authors.lastname: Loew
authors.forename: Thierry
authors.initials: T
authors.lastname: Galli
mesh_terms: D000818:Animals; D019556:COS Cells; D000081247:CSK Tyrosine-Protein Kinase; D002522:Chlorocebus aethiops; D005089:Exocytosis / Q000187:drug effects / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D010766:Phosphorylation / Q000502:physiology; D017434:Protein Structure, Tertiary; D050683:R-SNARE Proteins / Q000235:genetics / Q000378:metabolism*; D050600:SNARE Proteins / Q000235:genetics / Q000378:metabolism*; D019061:src-Family Kinases / Q000235:genetics / Q000378:metabolism
chemical_list: D007004:Hypoglycemic Agents; D007328:Insulin; D050683:R-SNARE Proteins; D050600:SNARE Proteins; C121241:VAMP7 protein, human; D007334:Insulin-Like Growth Factor I; D000081247:CSK Tyrosine-Protein Kinase; D019061:src-Family Kinases; C000631346:CSK protein, human