Sadler Jessica B A, Bryant Nia J, Gould Gwyn W
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.
Department of Biology, University of York, Heslington YO10 5DD, United Kingdom
Mol Biol Cell. 2015 Feb 1;26(3):530-6. doi: 10.1091/mbc.E14-09-1368. Epub 2014 Dec 10.
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.
含GLUT4的囊泡与脂肪细胞的质膜融合是胰岛素作用的一个关键方面。这一过程由质膜t-SNARE复合体与囊泡v-SNARE或VAMP之间形成功能性可溶性N-乙基马来酰亚胺敏感因子附着蛋白受体（SNARE）复合体介导。t-SNARE复合体由Syntaxin4和SNAP23组成，虽然许多研究将VAMP2鉴定为v-SNARE，但其他研究表明VAMP3或VAMP8也可能发挥这一作用。在这里，我们对3T3-L1脂肪细胞中表达的所有VAMP的表达水平、分布和关联进行了表征，从而对该蛋白家族的所有成员在任何细胞类型中进行了首次系统分析。尽管我们发现在体外所有VAMP异构体都能与Syntaxin4/SNAP23形成抗SDS的SNARE复合体，但结合表达水平（差异超过30倍）、亚细胞分布和共免疫沉淀分析，我们提出VAMP2是参与GLUT4转运至3T3-L1脂肪细胞质膜表面的主要v-SNARE。
