Martin D W, Tomkins G M, Bresler M A
Proc Natl Acad Sci U S A. 1969 Jul;63(3):842-9. doi: 10.1073/pnas.63.3.842.
The control of synthesis of the steroid-inducible enzyme, tyrosine aminotransferase (TAT), has been studied in synchronized cultures of HTC cells, an established line of rat hepatoma cells. During the mitotic and early G1 periods of the generation cycle of cells previously exposed to inducer, TAT synthesis is maximal in the absence of inducer, i.e., synthesis is constitutive. (By contrast, in random cells maximal TAT synthesis is always dependent upon the presence of the inducer.) After the third hour of G1 "G1[3]"), TAT synthesis is inhibited by a specific posttranscriptional repressor, the formation of which requires RNA synthesis. We speculate that this repressor is antagonized by the steroid inducer. The degradation of TAT during mitosis and G1 is constant and not affected by cycloheximide or actinomycin D in our experiments.
在已建立的大鼠肝癌细胞系HTC细胞的同步培养物中，对类固醇诱导型酶酪氨酸转氨酶（TAT）的合成调控进行了研究。在先前暴露于诱导剂的细胞生成周期的有丝分裂期和早期G1期，TAT合成在无诱导剂的情况下达到最大值，即合成是组成型的。（相比之下，在随机细胞中，TAT的最大合成总是依赖于诱导剂的存在。）在G1期的第三个小时（“G1[3]”）之后，TAT合成受到一种特异性转录后阻遏物的抑制，该阻遏物的形成需要RNA合成。我们推测这种阻遏物被类固醇诱导剂拮抗。在我们的实验中，有丝分裂期和G1期期间TAT的降解是恒定的，不受环己酰亚胺或放线菌素D的影响。
