Jin D H, Jung Y W, Ko B H, Moon I S
Department of Anatomy, College of Medicine, Dongguk University, Kyongju, Korea.
Mol Cells. 1997 Dec 31;7(6):749-54.
Quantitative immunoblot analyses were carried out to study the distribution of N-methyl-D-aspartate (NMDA) receptor subunit 2A and 2B (NR2A and NR2B, respectively) at the protein level in the adult rat brain. Highest levels of NR2A were detected in cerebral cortex and hippocampus, followed at more or less similar levels (about 36-72% of cerebral cortex) by striatum, thalamus, olfactory bulb, superior and inferior colliculi, and cerebellum. The lowest levels were detected in midbrain and lower brain stem (30-31% of cerebral cortex). The NR2B was more dramatic in differential distribution than the NR2A. Highest levels of NR2B were found in telencephalic (olfactory bulb, cerebral cortex, hippocampus, and striatum) and thalamic regions, and expression in superior and inferior colliculi, midbrain, lower brain stem, and cerebellum were significantly lower (4-25% of cerebral cortex). Interestingly, NR2B proteins were barely detectable in the cerebellum. When the postsynaptic density (PSD) fractions were compared, the amount of NR2B in the cerebellar PSD fraction was only 1.8% of that present in the cerebral PSD fraction where the subunit is highly enriched. Immunoblot analyses with a phosphotyrosine-specific antibody showed that the molecular sizes of major phosphotyrosine-containing proteins in forebrain and hindbrain are 180 and 45 kDa, respectively. The regional distribution of the 180 kDa major phosphotyrosine protein was very similar to that of NR2B, and the protein could be immunoprecipitated by NR2B antibody. Our data shows that NR2A and NR2B subunits are differentially distributed in the brain in an overlapping manner, and that the major phosphotyrosine-containing protein of 180 kDa in forebrain is the NR2B.
进行了定量免疫印迹分析，以研究成年大鼠脑中N-甲基-D-天冬氨酸（NMDA）受体亚基2A和2B（分别为NR2A和NR2B）在蛋白质水平的分布。在大脑皮层和海马中检测到最高水平的NR2A，其次是纹状体、丘脑、嗅球、上丘和下丘以及小脑，其水平或多或少相似（约为大脑皮层的36 - 72%）。在中脑和低位脑干中检测到最低水平（为大脑皮层的30 - 31%）。NR2B的差异分布比NR2A更为显著。在端脑（嗅球、大脑皮层、海马和纹状体）和丘脑区域发现NR2B的最高水平，而上丘和下丘、中脑、低位脑干和小脑中的表达明显较低（为大脑皮层的4 - 25%）。有趣的是，在小脑中几乎检测不到NR2B蛋白。当比较突触后致密部（PSD）组分时，小脑PSD组分中NR2B的量仅为该亚基高度富集的大脑PSD组分中NR2B量的1.8%。用磷酸酪氨酸特异性抗体进行的免疫印迹分析表明，前脑和后脑主要含磷酸酪氨酸蛋白的分子大小分别为180 kDa和45 kDa。180 kDa主要含磷酸酪氨酸蛋白的区域分布与NR2B非常相似，并且该蛋白可被NR2B抗体免疫沉淀。我们的数据表明，NR2A和NR2B亚基在大脑中以重叠的方式差异分布，并且前脑中180 kDa的主要含磷酸酪氨酸蛋白是NR2B。
