Sorimachi K, Yasumura Y
Jpn J Exp Med. 1983 Feb;53(1):33-9.
Concanavalin (Con A) induced tyrosine aminotransferase activity in cultured rat hepatoma cells (R117-21B). The highest level of the induced enzyme activity was observed at 6 to 8 hr of incubation with Con A, and the activity returned to the control level after 24 hr. This enzyme induction was dose-dependent in the range of 0.5 to 5 micrograms Con A per ml, while at higher concentrations (more than 50 micrograms/ml) the induction was very small or absent. The addition of alpha-methyl-D-mannoside abolished the effect of Con A. A 4 hr incubation of the cells with Con A and a subsequent 2 hr incubation was necessary to yield the maximal induction of tyrosine aminotransferase activity. Simultaneous incubation of the cells with Con A (5 micrograms/ml) and insulin or dexamethasone, induced tyrosine aminotransferase activity to levels higher than each activator alone, and the effect of Con A on the induction of tyrosine aminotransferase activity by dexamethasone was almost an additive. It was concluded that Con A at low concentrations mimics insulin in the induction of tyrosine aminotransferase activity in R117-21B cells, and that the effect of Con A and insulin on the induction of the enzyme is different from the effect of dexamethasone on this process.
伴刀豆球蛋白A（Con A）可诱导培养的大鼠肝癌细胞（R117 - 21B）中的酪氨酸转氨酶活性。在用Con A孵育6至8小时时观察到诱导酶活性的最高水平，24小时后活性恢复到对照水平。在每毫升0.5至5微克Con A的范围内，这种酶诱导呈剂量依赖性，而在较高浓度（超过50微克/毫升）时，诱导作用非常小或不存在。添加α-甲基-D-甘露糖苷可消除Con A的作用。细胞先用Con A孵育4小时，随后再孵育2小时，对于产生酪氨酸转氨酶活性的最大诱导是必要的。将细胞与Con A（5微克/毫升）以及胰岛素或地塞米松同时孵育，可将酪氨酸转氨酶活性诱导至高于每种激活剂单独作用时的水平，并且Con A对地塞米松诱导酪氨酸转氨酶活性的作用几乎是相加的。得出的结论是，低浓度的Con A在诱导R117 - 21B细胞中的酪氨酸转氨酶活性方面模拟胰岛素，并且Con A和胰岛素对该酶诱导的作用与地塞米松对这一过程的作用不同。
