title: Characterization of VAMP isoforms in 3T3-L1 adipocytes: implications for GLUT4 trafficking.
abstract: The fusion of GLUT4-containing vesicles with the plasma membrane of adipocytes is a key facet of insulin action. This process is mediated by the formation of functional soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complexes between the plasma membrane t-SNARE complex and the vesicle v-SNARE or VAMP. The t-SNARE complex consists of Syntaxin4 and SNAP23, and whereas many studies identify VAMP2 as the v-SNARE, others suggest that either VAMP3 or VAMP8 may also fulfil this role. Here we characterized the levels of expression, distribution, and association of all the VAMPs expressed in 3T3-L1 adipocytes to provide the first systematic analysis of all members of this protein family for any cell type. Despite our finding that all VAMP isoforms form SDS-resistant SNARE complexes with Syntaxin4/SNAP23 in vitro, a combination of levels of expression (which vary by >30-fold), subcellular distribution, and coimmunoprecipitation analyses lead us to propose that VAMP2 is the major v-SNARE involved in GLUT4 trafficking to the surface of 3T3-L1 adipocytes.
authors.affiliation: Henry Wellcome Laboratory of Cell Biology, Institute for Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom.
authors.forename: Jessica B A
authors.initials: JB
authors.lastname: Sadler
authors.affiliation: Department of Biology, University of York, Heslington YO10 5DD, United Kingdom Gwyn.Gould@Glasgow.ac.uk Nia.Bryant@York.ac.uk.
authors.forename: Nia J
authors.initials: NJ
authors.lastname: Bryant
authors.affiliation: Henry Wellcome Laboratory of Cell Biology, Institute for Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom Gwyn.Gould@Glasgow.ac.uk Nia.Bryant@York.ac.uk.
authors.forename: Gwyn W
authors.initials: GW
authors.lastname: Gould
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D051275:Glucose Transporter Type 4 / Q000378:metabolism*; D007328:Insulin / Q000494:pharmacology*; D051379:Mice; D020033:Protein Isoforms / Q000378:metabolism; D021381:Protein Transport; D050765:Qa-SNARE Proteins / Q000378:metabolism; D050766:Qb-SNARE Proteins / Q000378:metabolism; D050767:Qc-SNARE Proteins / Q000378:metabolism; D050683:R-SNARE Proteins / Q000378:metabolism*; D050988:Vesicle-Associated Membrane Protein 2 / Q000378:metabolism*
chemical_list: D051275:Glucose Transporter Type 4; D007328:Insulin; D020033:Protein Isoforms; D050765:Qa-SNARE Proteins; D050766:Qb-SNARE Proteins; D050767:Qc-SNARE Proteins; D050683:R-SNARE Proteins; C495693:Slc2a4 protein, mouse; C107017:Snap23 protein, mouse; D050988:Vesicle-Associated Membrane Protein 2; C494808:vesicle-associated membrane protein 2, mouse