EVIDENCE FOR 2 TYPES OF MEDIATION OF NEUTRAL AMINO-ACID TRANSPORT IN EHRILICH CELLS
EVIDENCE FOR 2 TYPES OF MEDIATION OF NEUTRAL AMINO-ACID TRANSPORT IN EHRILICH CELLS
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DOI：
10.1038/197765a0
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发表时间：
1963-01-01
期刊：
影响因子：
64.8
通讯作者：
CHRISTENSEN, HN
中科院分区：
文献类型：
--
作者：
OXENDER, DL;CHRISTENSEN, HN
对于相同的水平，氨基酸利用位点4进入，如甘氨酸和丙氨酸，流出量远远小于它们的流入量;因此，它们积累到高化学梯度。Tho amino.倾向于亮氨酸位点的酸显示出流出与它们的流入非常接近;因此，它们给出非常低的或稳态的分配比，在1和5之间。由于所有氨基酸之间的外排不依赖于内流，因此它们的初始摄取速率与它们的稳态分配比没有固定的关系。代表性的三组氨基酸的分配比随时间的变化如图2所示。甘氨酸具有最慢的初始进入速率，但最终积累到很高的程度。相比之下，亮氨酸具有最快的初始速率之一，但其最终分配比仅为3。甲硫氨酸和1-氨基-环戊烷羧酸具有高的初始进入速率，并积累到相对高的分配比。显然，如果甘氨酸最终被如此强烈地浓缩，尽管它的吸收相对较慢，但它从细胞中损失的速度必须更慢。美国甘氨酸，
For the same levels, the effluxes of amino-acids using site 4 for entry, such as glycine and alanine, are considerably smaller than their influxes; therefore, they are accumulated to high chemical gradients. Tho amino. acids preferring the leucine site show effluxes much closor to their influxes; accordingly, they give much lowor steady-state distribution ratios, between 1 and 5. Because efflux among all the amino-acids varies independontly of influx, thoir initial rates of uptako bear no fixed relationship to their steady-state distribution ratio. The change of the distribution ratio of representativos of the thro, groups of amino-acids with time is presented in Fig. 2. Glycine has the slowest initial entry rate but is eventually accumulated to a high degree. In contrast, leucine has one of the fastest initial rates, but it reaches a final distribution ratio of only 3. Methionino and 1-amino-cyclopentanecarboxylic acid have high initial rates of entry, and are accumulated to relatively high distribution ratios. Obviously if glycine is finally concentrated so strongly, despite its comparatively slow uptake it must be lost from the cell even more slowly. uS GLYCINE,