Department of Psychiatry and Biobehavioral Sciences, Semel Institute for Neuroscience and Human Behavior, Hatos Center for Neuropharmacology, David Geffen School of Medicine, UCLA, Los Angeles, California 90095-1761, USA.
J Biol Chem. 2010 Mar 5;285(10):6867-78. doi: 10.1074/jbc.M109.073064. Epub 2010 Jan 6.
Vesicular neurotransmitter transporters must localize to synaptic vesicles (SVs) to allow regulated neurotransmitter release at the synapse. However, the signals required to localize vesicular proteins to SVs in vivo remain unclear. To address this question we have tested the effects of mutating proposed trafficking domains in Drosophila orthologs of the vesicular monoamine and glutamate transporters, DVMAT-A and DVGLUT. We show that a tyrosine-based motif (YXXY) is important both for DVMAT-A internalization from the cell surface in vitro, and localization to SVs in vivo. In contrast, DVGLUT deletion mutants that lack a putative C-terminal trafficking domain show more modest defects in both internalization in vitro and trafficking to SVs in vivo. Our data show for the first time that mutation of a specific trafficking motif can disrupt localization to SVs in vivo and suggest possible differences in the sorting of VMATs versus VGLUTs to SVs at the synapse.
囊泡神经递质转运体必须定位于突触小泡 (SVs) 才能在突触处进行调节性神经递质释放。然而，目前尚不清楚将囊泡蛋白定位到 SVs 的体内所需的信号。为了解决这个问题，我们测试了改变果蝇中囊泡单胺和谷氨酸转运体的同源物 DVMAT-A 和 DVGLUT 中提出的运输结构域的效果。我们发现，酪氨酸基基序 (YXXY) 对于 DVMAT-A 从体外细胞表面内化以及体内定位于 SVs 都很重要。相比之下，缺乏推定的 C 末端运输结构域的 DVGLUT 缺失突变体在体外内化和体内 SVs 转运方面表现出更为适度的缺陷。我们的数据首次表明，特定运输基序的突变会破坏体内 SVs 的定位，并表明 VMATs 与 VGLUTs 在突触处 SVs 分拣方面可能存在差异。
