Schutz G, Killewich L, Chen G, Feigelson P
Proc Natl Acad Sci U S A. 1975 Mar;72(3):1017-20. doi: 10.1073/pnas.72.3.1017.
Glucocorticoid hormones increase the level of hepatic tryptophan oxygenase (EC 1.13.11.11; L-tryptophan:oxygen 2,3-oxidoreductase (decyclizing) by increasing its rate of synthesis. Studies were performed to determine whether this induction is mediated by controlling the level of the mRNA for tryptophan oxygenase of by changing the translational efficiency of a fixed level of mRNA. Activity of tryptophan oxygenase mRNA was quantitated in a Krebs ascites cell-free, protein-synthesizing system, supplemented with tRNA and rabbit reticulocyte initiation factors. De novo synthesis of the protomeric unit(s) of the enzyme was a linear function of the amount of mRNA added. Time course and dose-response studies in which the enzyme level and mRNA activity in livers from rats injected with inducing doses of hydrocortisone were compared indicate that the induction of this enzyme is accompanied by a proportional increase in the level of its mRNA. This was true for mRNA isolated from total liver as well as from cytoplasmic polysomes. Induction of the enzyme by its substrate, tryptophan, however, was not accompanied by a parallel increase in mRNA activity.
糖皮质激素通过提高肝色氨酸加氧酶（EC 1.13.11.11；L-色氨酸：氧2,3-氧化还原酶（脱环化））的合成速率来增加其水平。开展了多项研究以确定这种诱导作用是通过控制色氨酸加氧酶的mRNA水平还是通过改变固定水平mRNA的翻译效率来介导的。在补充了tRNA和兔网织红细胞起始因子的无细胞Krebs腹水蛋白质合成系统中对色氨酸加氧酶mRNA的活性进行了定量。该酶原聚体单位的从头合成是所添加mRNA量的线性函数。对注射诱导剂量氢化可的松的大鼠肝脏中的酶水平和mRNA活性进行比较的时间进程和剂量反应研究表明，该酶的诱导伴随着其mRNA水平的成比例增加。从全肝以及细胞质多聚核糖体分离的mRNA均是如此。然而，其底物色氨酸对该酶的诱导并未伴随着mRNA活性的平行增加。
