Quantitative Comparison of Glutamatergic and GABAergic Synaptic Vesicles Unveils Selectivity for Few Proteins Including MAL2, a Novel Synaptic Vesicle Protein
Quantitative Comparison of Glutamatergic and GABAergic Synaptic Vesicles Unveils Selectivity for Few Proteins Including MAL2, a Novel Synaptic Vesicle Protein
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DOI：
10.1523/jneurosci.4074-09.2010
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发表时间：
2010-01-06
影响因子：
5.3
通讯作者：
Jahn, Reinhard
中科院分区：
文献类型：
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作者：
Gronborg, Mads;Pavlos, Nathan J.;Jahn, Reinhard
突触小泡（SV）储存神经递质并通过胞吐作用释放它们。囊泡神经递质转运蛋白区分哪些递质将被囊泡隔离和储存。然而，尚不清楚 SV 的神经递质表型是否仅由转运蛋白定义，或者是否与其他蛋白质相关。在这里，我们使用定量蛋白质组学比较了分别富含囊泡谷氨酸 (VGLUT-1) 和 GABA 转运蛋白 (VGAT) 的 SV 的蛋白质组成。在超过 450 种定量蛋白质中，有大约 50 种蛋白质在群体之间存在差异分布，其中只有少数是 SV 特异性的。其中，最显着的差异是锌转运蛋白 ZnT3 以及优先与 VGLUT-1 囊泡相关的囊泡蛋白 SV2B 和 SV31，以及主要与 VGAT 囊泡相关的 SV2C。令人惊讶的是，其他几种蛋白质表现出对 VGLUT-1 囊泡的偏好，其中包括突触素、突触结合蛋白和突触结合蛋白 1a。此外，MAL2（一种功能未知的膜蛋白，与突触素和 SCAMP 关系较远）与 VGLUT-1 囊泡共同分级。光和电子显微镜水平上的亚细胞分级和免疫定位都表明，MAL2 是 SV 的真正膜成分，优先与含有 VGLUT-1 的神经末梢相关。我们得出的结论是，不同神经递质特异的 SV 共享其大部分蛋白质成分，只有少数囊泡蛋白表现出非排他性的偏好，从而证实囊泡转运蛋白是定义 SV 神经递质表型所必需的唯一成分。
Synaptic vesicles (SVs) store neurotransmitters and release them by exocytosis. The vesicular neurotransmitter transporters discriminate which transmitter will be sequestered and stored by the vesicles. However, it is unclear whether the neurotransmitter phenotype of SVs is solely defined by the transporters or whether it is associated with additional proteins. Here we have compared the protein composition of SVs enriched in vesicular glutamate (VGLUT-1) and GABA transporters (VGAT), respectively, using quantitative proteomics. Of >450 quantified proteins, similar to 50 were differentially distributed between the populations, with only few of them being specific for SVs. Of these, the most striking differences were observed for the zinc transporter ZnT3 and the vesicle proteins SV2B and SV31 that are associated preferentially with VGLUT-1 vesicles, and for SV2C that is associated mainly with VGAT vesicles. Several additional proteins displayed a preference for VGLUT-1 vesicles including, surprisingly, synaptophysin, synaptotagmins, and syntaxin 1a. Moreover, MAL2, a membrane protein of unknown function distantly related to synaptophysins and SCAMPs, cofractionated with VGLUT-1 vesicles. Both subcellular fractionation and immunolocalization at the light and electron microscopic level revealed that MAL2 is a bona-fide membrane constituent of SVs that is preferentially associated with VGLUT-1-containing nerve terminals. We conclude that SVs specific for different neurotransmitters share the majority of their protein constituents, with only few vesicle proteins showing preferences that, however, are nonexclusive, thus confirming that the vesicular transporters are the only components essential for defining the neurotransmitter phenotype of a SV.