Localization and subcellular distribution of N-copine in mouse brain
Localization and subcellular distribution of N-copine in mouse brain
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DOI：
10.1046/j.1471-4159.1999.0720373.x
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发表时间：
1999-01-01
影响因子：
4.7
通讯作者：
Kuwajima, G
中科院分区：
文献类型：
--
作者：
Nakayama, T;Yaoi, T;Kuwajima, G
N-Copine是一种具有两个C2结构域的新蛋白质。它的表达是大脑特有的，并受到神经元活动的上调，如海人酸电刺激和破伤风刺激，从而引起海马CA1区长时程增强。我们研究了N-Copine在小鼠脑内的定位和亚细胞分布。原位杂交分析表明，N-Copine mRNA仅在海马神经元、主嗅球和副嗅球中表达，在那里发生了各种形式的突触可塑性和记忆形成。在免疫组织化学分析中，N-Copine主要在神经元的胞体和树突中检测到，而突触前蛋白如突触前蛋白I和Rab3A在轴突通过的区域被检测到。在脑匀浆的分级实验中，N-Copine在有Ca~(2+)存在的情况下与膜组分有联系，而在无Ca~(2+)的情况下则不存在。由于N-Copine的第二个C2结构域与GST融合蛋白与磷脂酰丝氨酸的结合依赖于钙离子，该结构域被认为是N-Copine与膜的钙依赖结合的原因。因此，N-Copine可能在突触后事件中起到钙感受器的作用，而不是已知的“双C2结构域蛋白”在突触前事件中的作用，包括突触聚集素I。
N-Copine is a novel protein with two C2 domains. Its expression is brain specific and up-regulated by neuronal activity such as kainate stimulation and tetanus stimulation evoking hippocampal CA1 long-term potentiation. We examined the localization and subcellular distribution of N-copine in mouse brain. In situ hybridization analysis showed that N-copine mRNA was expressed exclusively in neurons of the hippocampus and in the main and accessory olfactory bulb, where various forms of synaptic plasticity and memory formation are known to occur. In immunohistochemical analyses, N-copine was detected mainly in the cell bodies and dendrites in the neurons, whereas presynaptic proteins such as synaptotagmin I and rab3A were detected in the regions where axons pass through. In fractionation experiments of brain homogenate, N-copine was associated with the membrane fraction in the presence of Ca2+ but not in its absence. As a GST-fusion protein with the second C2 domain of N-copine showed Ca2+-dependent binding to phosphatidylserine, this domain was considered to be responsible for the Ca2+-dependent association of N-copine with the membrane. Thus, N-copine may have a role as a Ca2+ sensor in postsynaptic events, in contrast to the known roles of "double C2 domain-containing proteins," including synaptotagmin I, in presynaptic events.