Biochemical Studies on neurotransm tter transporters in syhoptic vesica

突触小泡在神经末梢的神经元传递中起着重要作用。它们积聚了高浓度的神经递质，在收到适当的信号后，通过胞吐作用将其分泌出来。我们发现，囊泡上的液泡ATPase形成了跨膜的质子的电化学梯度，并且递质通过与该梯度耦合的特定转运体被摄取。然而，人们对转运蛋白的生化特性知之甚少。本研究旨在阐明转运蛋白和液泡型ATPase的一些生化性质。两年来，我们取得了以下成果。(1)谷氨酸转运体的能量耦合，转运体由膜电位驱动，而其他转运体由DELTApH驱动。(2)建立了细菌F-ATPase重组转运蛋白的方法。该方法可用于转运蛋白纯化的检测系统。(3)我们发现谷氨酸二苄酯是谷氨酸转运体的有效抑制剂。(4)我们发现突触小泡多巴胺转运体识别甲基苯基吡啶(MPP^+)为底物。这些结果为进一步研究递质转运蛋白的生化特性提供了基础信息。

Synaptic vesicles play an important role in neuronal transmission in nerve termini. They accumulate high concentrations of neurotransmitters and , upon receiving the proper signal, secrete them by exocytosis. We found that vacuolar ATPase on the vesicles forms an electrochemical gradient of protons across the membranes and transmitters are taken up through specific transporters coupled with this gradient. However, little is known about biochemical properties on the transporters. This study was focused to elucidate some biochemical properties on the transporter and vacuolar ATPase. During the two years, we obtained following results. (1) Energy coupling of glutamate transporter, the transporter is driven by membrane potential but other transporters are driven by DELTApH. (2) We established a procedure for reconstitution of transporter with bacterial F-ATPase. The procedure can be used for the assay system for purification of transporter. (3) We identified dibenzylglutamate as potent inhibitor for glutamate transporter. (4) We found that synaptic vesicle dopamine transpoter recognized methlphenylpyridinium (MPP^+), as a substrate. These results give basic information for the further biochemical study of transmitter transporters.