Oxender D L, Lee M, Cecchini G
Prog Clin Biol Res. 1976;9:41-7.
The regulation of amino acid transport has been investigated in Balb/3T3 cells. Transport for neutral amino acids in animal tissues is carried out by two distinct systems. The transport activity of the A system (alanine preferring) is inhibited by high internal of substrate amino acids, a process termed trans-inhibition. In contrast, the L system transport activity is greatly stimulated by high internal levels of substrate, a phenomenon termed trans-stimulation. Regulation of amino acid transport in animal cells occurs by a repression-derepression mechanism or by a feedback inhibition or feedback stimulation process. The level of endogenous amino acids is shown to be important in the regulation of transport activity. Cells which are slow growing or quiescent have increased levels of endogenous amino acids, which in turn effect the transport activity. The A system transport activity is decreased in quiescent cells, whereas L system transport activity increases. Conditions which effect endogenous amino acid levels have an effect on transport activity. Feedback regulation of transport activity through the amino acid pool levels is another way animal cells can regulate transport activity.
已在Balb/3T3细胞中研究了氨基酸转运的调节。动物组织中中性氨基酸的转运由两个不同的系统进行。A系统（优先转运丙氨酸）的转运活性受到底物氨基酸高细胞内浓度的抑制，这一过程称为反抑制。相反，L系统的转运活性受到底物高细胞内水平的极大刺激，这一现象称为反刺激。动物细胞中氨基酸转运的调节通过阻遏-去阻遏机制或反馈抑制或反馈刺激过程发生。内源性氨基酸水平在转运活性调节中显示出重要性。生长缓慢或静止的细胞内源性氨基酸水平升高，这反过来又影响转运活性。静止细胞中A系统的转运活性降低，而L系统的转运活性增加。影响内源性氨基酸水平的条件会对转运活性产生影响。通过氨基酸池水平对转运活性进行反馈调节是动物细胞调节转运活性的另一种方式。
