Cationic amino acid transport in the rabbit reticulocyte. Na+-dependent inhibition of Na+-independent transport.
Cationic amino acid transport in the rabbit reticulocyte. Na+-dependent inhibition of Na+-independent transport.
复制标题
兔网织红细胞中的阳离子氨基酸转运。
DOI：
10.1016/s0021-9258(18)91787-4
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发表时间：
1969
期刊：
影响因子：
--
通讯作者：
J. Antonioli
中科院分区：
文献类型：
--
作者：
H. Christensen;J. Antonioli
描述了兔网织细胞的阳离子氨基酸运输系统。这个系统看起来既不集中也不依赖能量。在高水平上，一些具有大极性侧链的中性氨基酸抑制它的摄取；此外，外部亮氨酸的存在加速了赖氨酸从细胞中流出。然而，这些效应不是由新系统与主要的Na+不依赖系统之间的相互作用引起的，这些氨基酸通过该系统运输，因为2-氨基双环[2,2,1]庚烷-2-羧酸，后者系统的一种新的特异性底物，对二氨基酸的摄取没有抑制作用。此外，赖氨酸对亮氨酸的摄取没有抑制作用。尽管上述关系可以在Na+存在或不存在的情况下显示出来，但当Na+在约0.14M时存在时，所测试的碱性氨基酸的吸收速度要快10%至50%。明确的证据表明，Na+刺激部分代表一个独立的系统尚未获得。在Na+存在的情况下，半胱氨酸和同丝氨酸对二氨基酸摄取的抑制作用要比受Na+刺激的部分大得多，而在Na+不存在的情况下则没有抑制作用。结果是，当过量添加这两种氨基酸中的一种时，Na+从刺激物变成了二氨基酸运输的抑制剂。
A transport system for cationic amino acids has been described for the rabbit reticulocyte. This system appears neither concentrative nor energy-dependent. At high levels, several neutral amino acids with large apolar side chains inhibit uptake by it; furthermore, the presence of external leucine accelerates lysine exodus from the cell. These effects do not, however, arise from an interaction between the new system and the dominant Na+-independent system by which these amino acids are transported, because 2-aminobicyclo[2,2,1]heptane-2-carboxylic acid, a new specific substrate for the latter system, shows no inhibition of diamino acid uptake. Furthermore, lysine is devoid of inhibitory action on leucine uptake.Although the relations described above can be shown either in the presence or absence of Na+, the basic amino acids tested are taken up from 10 to 50% more rapidly when Na+is present at about 0.14M. Unequivocal evidence that the Na+-stimulated portion represents an independent system has not been obtained. In the presence of Na+, cysteine and homoserine inhibit a substantially larger portion than the Na+-stimulated portion of the uptake of diamino acids whereas no inhibition is seen in the absence of Na+. The result is that, on the addition of one of these two amino acids in excess, Na+is changed from a stimulant to an inhibitor of diamino acid transport.