STEADY-STATES, CHARGE MOVEMENTS, AND RATES FOR A CLONED GABA TRANSPORTER EXPRESSED IN XENOPUS OOCYTES
STEADY-STATES, CHARGE MOVEMENTS, AND RATES FOR A CLONED GABA TRANSPORTER EXPRESSED IN XENOPUS OOCYTES
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DOI：
10.1016/0896-6273(93)90309-f
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发表时间：
1993-02-01
期刊：
影响因子：
16.2
通讯作者：
LESTER, HA
中科院分区：
文献类型：
--
作者：
MAGER, S;NAEVE, J;LESTER, HA
应用电压钳分析研究了非洲爪蟾卵母细胞高效表达的克隆转运蛋白GAT 1摄取细胞外γ-氨基丁酸（GABA）的电流。稳态GABA电流增加，在更高的细胞外[GABA]，[Na+]，[Cl-]和更多的负电位。Na+的Hill系数超过1，表明涉及两个Na+离子。在没有GABA的情况下，电压跳变产生瞬态电流，表现得像电容性电荷运动;这些被抑制的摄取抑制剂SKF-89976 A，转移到更负的电位在较低的外部[Na+]和[Cl-]，并有一个有效价1.1元电荷。电压跃变弛豫动力学和最大GABA电流与电荷运动之间的比率均给出了最大[GABA]（-80 mV，96 mM NaCl，22 ℃）时每个转运蛋白的周转率为6-13/s。这些定量数据对于评估GAT 1在突触功能中的作用是必要的。
Voltage-clamp analysis was applied to study the currents associated with the uptake of extracellular gamma-amino-butyric acid (GABA) by the cloned transporter GAT1 expressed at high efficiency in Xenopus oocytes. Steady-state GABA currents were increased at higher extracellular [GABA], [Na+], and [Cl-] and at more negative potentials. The Hill coefficient for Na+ exceeded unity, suggesting the involvement of two Na+ ions. In the absence of GABA, voltage jumps produced transient currents that behaved like capacitive charge movements; these were suppressed by the uptake inhibitor SKF-89976A, were shifted to more negative potentials at lower external [Na+] and [Cl-], and had an effective valence of 1.1 elementary charge. A turnover rate per transporter of 6-13/s at maximal [GABA] (-80 mV, 96 mM NaCl, 22-degrees-C) is given both by the kinetics of voltage jump relaxations and by the ratio between the maximal GABA currents and the charge movements. These quantitative data are necessary for evaluating the roles of GAT1 in synaptic function.