Steinberg R A, Levinson B B, Tomkins G M
Proc Natl Acad Sci U S A. 1975 Jun;72(6):2007-11. doi: 10.1073/pnas.72.6.2007.
The specific rate of synthesis of tyrosine aminotransferase (EC 2.6.1.5; L-tyrosine:2-oxoglutarate aminotransferase) is used as a measure of the level of functional, cytoplasmic, tyrosine aminotransferase-specific mRNA in cultured rat hepatoma cells. An analysis of the kinetics of change in this rate after the addition or withdrawal of glucocorticosteroids sets an upper limit on the half-life of the enzyme-specific mRNA of 1-1.5 hr, whether or not steroid is present. The inactivation rate of the enzyme mRNA is independent of the growth condition of the cells, occuring equally rapidly in the presence or absence of serum or insulin, both of which induce tyrosine aminotransferase in these cells. The implications of these results for the mechanism of steroid induction are discussed.
酪氨酸转氨酶(EC 2.6.1.5;L-酪氨酸:2-氧代戊二酸转氨酶)的合成比速率被用作衡量培养的大鼠肝癌细胞中功能性细胞质酪氨酸转氨酶特异性mRNA水平的指标。在添加或去除糖皮质激素后,对该速率变化动力学的分析确定了无论是否存在类固醇,酶特异性mRNA的半衰期上限为1 - 1.5小时。酶mRNA的失活速率与细胞的生长条件无关,在有或无血清或胰岛素的情况下均同样迅速地发生,而血清和胰岛素均可诱导这些细胞中的酪氨酸转氨酶。讨论了这些结果对类固醇诱导机制的意义。