Bjørås M, Gjesdal O, Erickson J D, Torp R, Levy L M, Ottersen O P, Degree M, Storm-Mathisen J, Seeberg E, Danbolt N C
Anatomical Institute, University of Oslo, Norway.
Brain Res Mol Brain Res. 1996 Feb;36(1):163-8. doi: 10.1016/0169-328x(95)00279-2.
Glutamate is the major excitatory transmitter in the mammalian central nervous system. Glutamate transporters, which keep the extracellular glutamate concentration low, are required both for normal brain function and for protecting neurons against harmful glutamatergic overstimulation. We have isolated the cDNA for a rat brain glutamate transporter (REAAC1) which has 90% amino acid and 86% nucleotide identity to the rabbit EAAC1. When REAAC1 was expressed in HeLa cells using a recombinant vaccinia-T7 virus expression system, a sodium dependent glutamate uptake was observed. The affinity of the carrier to various substrates was typical of brain "high affinity' glutamate uptake: threo-3-hydroxyaspartate, (R)-aspartate, (S)-glutamate and (S)-trans-pyrrolidine-2,4-dicarboxylic acid were strong inhibitors, but not (R)-glutamate or gamma-aminobutyrate. High resolution, non-radioactive in situ hybridization histochemistry in rat brain revealed the mRNA in several types of glutamatergic as well as non-glutamatergic neurons, but not in glial cells.
谷氨酸是哺乳动物中枢神经系统中的主要兴奋性神经递质。谷氨酸转运体可使细胞外谷氨酸浓度保持在较低水平，对于正常脑功能以及保护神经元免受有害的谷氨酸能过度刺激均不可或缺。我们已分离出大鼠脑谷氨酸转运体（REAAC1）的cDNA，它与兔EAAC1的氨基酸同一性为90%，核苷酸同一性为86%。当使用重组痘苗-T7病毒表达系统在HeLa细胞中表达REAAC1时，观察到了钠依赖性谷氨酸摄取。该载体对各种底物的亲和力具有脑“高亲和力”谷氨酸摄取的典型特征：L-3-羟基天冬氨酸、L-天冬氨酸、D-谷氨酸和反式-L-脯氨酸-2,4-二羧酸是强抑制剂，但L-谷氨酸或γ-氨基丁酸不是。大鼠脑中的高分辨率非放射性原位杂交组织化学显示，几种谷氨酸能和非谷氨酸能神经元中有该mRNA，但胶质细胞中没有。
