Hanretta A T, Lombardini J B
Neurochem Res. 1987 Aug;12(8):705-13. doi: 10.1007/BF00970526.
Two uptake systems for taurine transport in a rat hypothalamic crude synaptosomal preparation were identified. The true transport constants were, for the high-affinity uptake system, Km = 240 microM and V (maximum velocity) = 400 nmol/g protein/min, and for the low-affinity uptake system, Km = 5290 microM and V = 1640 nmol/g protein/min. The initial velocity of high-affinity taurine uptake by the crude synaptosomal preparation was studied as a function of sodium and taurine concentration. Hill plots were constructed from these data. The requirement of high-affinity taurine uptake on a sodium gradient was examined by utilizing monensin, and the metabolic poisons, 2,4-dinitrophenol and ouabain. The major findings are as follows: 1) One sodium ion is co-transported with each taurine molecule; 2) the high-affinity uptake process is driven by the sodium concentration gradient across the membrane; 3) sodium increases the maximal velocity rather than the affinity of the high-affinity taurine carrier for the taurine molecule; 4) one taurine molecule is transported per carrier for both the high- and low-affinity taurine uptake systems; and 5) high-affinity taurine uptake is an energy-dependent process.
在大鼠下丘脑粗制突触体标本中鉴定出两种牛磺酸转运摄取系统。对于高亲和力摄取系统，真实转运常数为 Km = 240微摩尔，V（最大速度）= 400纳摩尔/克蛋白质/分钟；对于低亲和力摄取系统，Km = 5290微摩尔，V = 1640纳摩尔/克蛋白质/分钟。研究了粗制突触体标本对高亲和力牛磺酸摄取的初始速度与钠和牛磺酸浓度的函数关系。根据这些数据构建了希尔图。利用莫能菌素以及代谢毒物2,4-二硝基苯酚和哇巴因，研究了高亲和力牛磺酸摄取对钠梯度的需求。主要发现如下：1）每个牛磺酸分子与一个钠离子协同转运；2）高亲和力摄取过程由跨膜的钠浓度梯度驱动；3）钠增加了高亲和力牛磺酸载体对牛磺酸分子的最大速度而非亲和力；4）对于高亲和力和低亲和力牛磺酸摄取系统，每个载体均转运一个牛磺酸分子；5）高亲和力牛磺酸摄取是一个能量依赖过程。
