Synaptotagamin I and IV define distinct populations of neuronal transport vesicles
Synaptotagamin I and IV define distinct populations of neuronal transport vesicles
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DOI：
10.1046/j.1460-9568.2000.00013.x
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发表时间：
2000-04-01
影响因子：
3.4
通讯作者：
Marquèze, B
中科院分区：
文献类型：
--
作者：
Berton, F;Cornet, V;Marquèze, B
哺乳动物突触结合蛋白是一个由至少11种膜蛋白组成的多基因家族。我们已经使用针对蛋白质的C2 A结构域的抗体表征了突触结合蛋白IV。抗体与作为41-44 kDa双联体迁移的蛋白质条带特异性反应。Synaptotagmin IV的表达在整个发育过程中受到调节。免疫印迹法检测到的量发生在出生后第5天和成年期之间，与突触结合蛋白IV转录本表达的研究一致。在亚细胞分馏，突触结合蛋白IV中没有检测到的突触囊泡富集部分。免疫荧光显微镜检查结果与此一致。在6日龄大鼠小脑和培养的海马神经元中，突触结合蛋白IV和突触结合蛋白I的亚细胞分布明显不同。Synaptotagmin IV在神经元延伸上显示点状非极化分布，而synaptotagmin I染色基本上是突触性的。突触结合蛋白IV染色也观察到在一些强烈的核周荧光斑点叠加的高尔基体/ TGN标记。此外，synaptotagmin IV被认为是在生长锥域的近端部分，而不是在microdelicent丰富的区域，其中包括丝状伪足。共定位与粘附分子纽蛋白和zyxin在近端部分的生长锥进行了观察。因此，突触结合蛋白IV可能参与大脑发育过程中特定膜运输途径的调节。
Mammalian synaptotagmins constitute a multigene family of at least 11 membrane proteins. We have characterized synaptotagmin IV using antibodies directed against the C2A domain of the protein. Antibodies reacted specifically with a protein band that migrated as a 41-44 kDa doublet. Synaptotagmin IV expression was regulated throughout development. A strong decrease in the amount detected by Western blotting occurred between postnatal day 5 and adulthood, in agreement with studies on the expression of synaptotagmin IV transcripts. In subcellular fractionation, synaptotagmin IV was not detected in the synaptic vesicle-enriched fraction. Immunofluorescence microscopy was concordant with this finding. In 6-day-old rat cerebellum and cultured hippocampal neurons the subcellular distribution of synaptotagmin IV was clearly different from that of synaptotagmin I. Synaptotagmin IV displayed a punctate non-polarized distribution on neuronal extensions, whereas synaptotagmin I staining was essentially synaptic. Synaptotagmin IV staining was also observed in the some in strong perinuclear fluorescent puncta superimposed on that of Golgi/ TGN markers. Furthermore, synaptotagmin IV was seen in the proximal part of the growth cone domain and not in the microfilament-rich region which includes filopodia. Co-localizations with the adhesion molecules vinculin and zyxin at the proximal part of growth cones were observed. Synaptotagmin IV may thus be involved in the regulation of specific membrane-trafficking pathways during brain development.