Tao-Cheng J-H
Electron Microscopy Facility, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Building 49, Room 3A50, Bethesda, MD 40892, USA.
Neuroscience. 2006 Sep 1;141(3):1217-24. doi: 10.1016/j.neuroscience.2006.04.061. Epub 2006 Jun 6.
Immunogold labeling distributions of seven presynaptic proteins were quantitatively analyzed under control conditions and after high K+ depolarization in excitatory synapses from dissociated rat hippocampal cultures. Three parallel zones in presynaptic terminals were sampled: zones I and II, each about one synaptic vesicle wide extending from the active zone; and zone III, containing a distal pool of vesicles up to 200 nm from the presynaptic membrane. The distributions of SV2 and synaptophysin, two synaptic vesicle integral membrane proteins, generally followed the distribution of synaptic vesicles, which were typically evenly distributed under control conditions and had a notable depletion in zone III after stimulation. Labels of synapsin I and synuclein, two synaptic vesicle-associated proteins, were similar to each other; both were particularly sparse in zone I under control conditions but showed a prominent enrichment toward the active zone, after stimulation. Labels of Bassoon, Piccolo and RIM 1, three active zone proteins, had very different distribution profiles from one another under control conditions. Bassoon was enriched in zone II, Piccolo and RIM 1 in zone I. After stimulation, Bassoon and Piccolo remained relatively unchanged, but RIM 1 redistributed with a significant decrease in zone I, and increases in zones II and III. These results demonstrate that Bassoon and Piccolo are stable components of the active zone while RIM 1, synapsin I and synuclein undergo dynamic redistribution with synaptic activity.
在解离的大鼠海马培养物兴奋性突触的对照条件下和高钾去极化后，对七种突触前蛋白的免疫金标记分布进行了定量分析。对突触前终末的三个平行区域进行了采样：区域I和区域II，每个区域从活性区延伸约一个突触小泡宽度；区域III，包含距离突触前膜最远达200 nm的远端小泡池。两种突触小泡整合膜蛋白SV2和突触素的分布通常遵循突触小泡的分布，在对照条件下突触小泡通常均匀分布，刺激后在区域III有明显减少。两种突触小泡相关蛋白突触结合蛋白I和突触核蛋白的标记彼此相似；在对照条件下，两者在区域I中都特别稀少，但刺激后向活性区显著富集。三种活性区蛋白巴松管蛋白、短笛蛋白和RIM 1在对照条件下具有彼此非常不同的分布模式。巴松管蛋白在区域II中富集，短笛蛋白和RIM 1在区域I中富集。刺激后，巴松管蛋白和短笛蛋白相对保持不变，但RIM 1重新分布，区域I中显著减少，区域II和区域III中增加。这些结果表明，巴松管蛋白和短笛蛋白是活性区的稳定成分，而RIM 1、突触结合蛋白I和突触核蛋白随着突触活动发生动态重新分布。
