REGULATION OF AMINO-ACID TRANSPORT IN CHICK-EMBRYO HEART-CELLS .1. ADAPTIVE SYSTEM OF MEDIATION FOR NEUTRAL AMINO-ACIDS
REGULATION OF AMINO-ACID TRANSPORT IN CHICK-EMBRYO HEART-CELLS .1. ADAPTIVE SYSTEM OF MEDIATION FOR NEUTRAL AMINO-ACIDS
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DOI：
10.1016/0005-2736(72)90097-1
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发表时间：
1972-01-01
期刊：
影响因子：
--
通讯作者：
FRANCHI, R
中科院分区：
文献类型：
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作者：
GAZZOLA, GC;GUIDOTTI, GG;FRANCHI, R
对鸡胚心细胞氨基酸转运系统的调节进行了研究。实验研究了在不同的体外条件下(蛋白质和RNA合成活跃和抑制、氨基酸依赖、反式抑制)下，类似物和天然氨基酸的转运活性和动力学随时间的变化。一组中性氨基酸的转运活性(与克里斯滕森和同事J.Biol的A调解相对应)。化学，238(1963)3686；Adv.Enzymol.，32(1969)1)在没有添加氨基酸的情况下培养细胞或完整的心脏时，随着时间的推移而增加。这种增加在普鲁霉素、放线菌亚胺和放线菌素D.2.2的存在下被取消。A运输系统活性的增加(以氨基异丁酸和脯氨酸为代表氨基酸进行研究)通过在竞争研究的基础上被分配给同一调节系统的氨基酸的孵育介质中的添加来防止。添加属于L调节系统的氨基酸或碱性氨基酸不会实质上改变它。反式抑制似乎不是调节A运输系统活动的主要因素。对A系统和L系统转运类似物的动力学分析进一步强调A转运系统是有效的(影响最大速度，Km没有明显变化)，并对以前报道的影响类似物转运的动力学参数随时间和细胞内底物浓度的变化提供了全面的解释。已经考虑了观察到的中性氨基酸的A运输系统活性的适应性调节的临时机制。
The regulation of amino acid transport systems in chick embryo heart cells has been studied. Experiments were designed to investigate activity and kinetics of transport for analogue and natural amino acids as a function of time under variousin vitroconditions (active and inhibited protein and RNA synthesis, amino acid dependence, transinhibition).Conclusions based on the proposed experimental approach include the following:1.1. The transport activity of a group of neutral amino acids (corresponding to those ascribed to the A mediation by Christensen and co-workers,J. Biol. Chem., 238(1963)3686;Adv. Enzymol., 32(1969)1) increases with time when cells or intact hearts are incubated in the absence of added amino acids. This increase is abolished in the presence of puromycin, cycloheximide and actinomycin D.2.2. The increase in activity of the A transport system (investigated by aminoisobutyrate and proline as representative amino acids) is prevented by the addition to the incubation medium of amino acids assigned to the same system of mediation on the basis of competition studies. It is not substantially altered by the addition of amino acids pertaining to the L system of mediation or basic amino acids.3.3. Transinhibition does not appear of major importance in the regulation of the activity of the A transport system.4.4. Kinetic analyses of aminoisobutyrate uptake in which the transport of the analogue by the A and L systems of mediation could be separated stress further that a time-dependent regulation is effective for the sole A transport system (affecting the maximal velocity without substantial changes inKm) and provide a comprehensive explanation for previously reported changes with time and intracellular substrate concentration of the kinetic parameters governing the uptake of the analogue9.5.5. Provisional mechanisms for the observed adaptive regulation of the activity of the A transport system for neutral amino acids have been considered.