Distribution of Kainate Receptor Subunits at Hippocampal Mossy Fiber Synapses
Distribution of Kainate Receptor Subunits at Hippocampal Mossy Fiber Synapses
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DOI：
10.1523/jneurosci.23-22-08013.2003
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发表时间：
2003-09
期刊：
影响因子：
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通讯作者：
M. Darstein;R. Petralia;G. Swanson;R. Wenthold;S. Heinemann
中科院分区：
文献类型：
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作者：
M. Darstein;R. Petralia;G. Swanson;R. Wenthold;S. Heinemann
红藻氨酸受体作为突触后电流的介质和作为苔藓纤维突触的突触传递的突触前调节剂发挥作用。尽管对苔藓纤维红藻氨酸受体的生理特性进行了深入的研究，但其在突触前和突触后区室中的亚基组成尚不清楚。在这里，我们描述的分布红藻氨酸受体亚单位苔藓纤维突触使用亚单位选择性抗体和基因敲除小鼠。我们提供了形态学证据的突触前本地化的KA 1和KA 2受体亚单位在苔藓纤维突触。KA 1和KA 2的免疫金染色常见于突触接触处和囊泡结构中。树突棘的突触后标记也被观察到。虽然KA 1主要表现出突触前定位，KA 2集中在更大程度上的突触后膜。这两个亚基共免疫沉淀从海马膜提取物与GluR6，但不GluR7亚基。这些结果表明，KA1和KA2亚基定位于突触前和突触后苔藓纤维突触，在那里他们最有可能与GluR6亚基共组装形成功能性异聚红藻氨酸受体复合物。
Kainate receptors function as mediators of postsynaptic currents and as presynaptic modulators of synaptic transmission at mossy fiber synapses. Despite intense research into the physiological properties of mossy fiber kainate receptors, their subunit composition in the presynaptic and postsynaptic compartments is unclear. Here we describe the distribution of kainate receptor subunits in mossy fiber synapses using subunit-selective antibodies and knock-out mice. We provide morphological evidence for the presynaptic localization of KA1 and KA2 receptor subunits at mossy fiber synapses. Immunogold staining for KA1 and KA2 was commonly seen at synaptic contacts and in vesicular structures. Postsynaptic labeling in dendritic spines was also observed. Although KA1 predominantly showed presynaptic localization, KA2 was concentrated to a greater degree on postsynaptic membranes. Both subunits coimmunoprecipitated from hippocampal membrane extracts with GluR6 but not GluR7 subunits. These results demonstrate that KA1 and KA2 subunits are localized presynaptically and postsynaptically at mossy fiber synapses where they most likely coassemble with GluR6 subunits to form functional heteromeric kainate receptor complexes.