Martin D W, Tomkins G M
Proc Natl Acad Sci U S A. 1970 Apr;65(4):1064-8. doi: 10.1073/pnas.65.4.1064.
The synthesis of the enzyme tyrosine aminotransferase in HTC cells (an established line of rat hepatoma cells) is inducible by glucocorticoid hormones only during the latter part of G1 phase and throughout S phase in the cell generation cycle. We have earlier shown that during the first few hours of G1 phase when the enzyme cannot be induced, its synthesis is constitutive, presumably using as template, preexisting messenger RNA. Our model for tyrosine aminotransferase gene regulation in eukaryotic cells entails a specific post-transcriptional repressor which is formed only during the periods in the cell cycle when tyrosine aminotransferase is inducible. This model predicts that during the noninducible period, G2, the tyrosine aminotransferase repressor would not be present and thus tyrosine aminotransferase synthesis would be constitutive. Data are presented which confirm this prediction in further support of the model.
HTC细胞（一种已建立的大鼠肝癌细胞系）中酪氨酸转氨酶的合成仅在细胞增殖周期的G1期后期及整个S期受糖皮质激素诱导。我们先前已表明，在G1期的最初几个小时内，当该酶无法被诱导时，其合成是组成型的，推测是以预先存在的信使RNA作为模板。我们关于真核细胞中酪氨酸转氨酶基因调控的模型涉及一种特定的转录后阻遏物，它仅在细胞周期中酪氨酸转氨酶可被诱导的时期形成。该模型预测，在不可诱导的时期G2期，酪氨酸转氨酶阻遏物将不存在，因此酪氨酸转氨酶的合成将是组成型的。所呈现的数据证实了这一预测，进一步支持了该模型。
