磷酸化对人肝癌细胞株SMMC-7721转醛醇酶活性的影响

目的:研究人肝癌细胞株SMMC-7721中转醛醇酶(Transaldolase,TAL)活性变化与磷酸化的关系。方法:SMMC-7721细胞培养,细胞周期同步化后分组加不同浓度(10%、1%)胎牛血清孵育,分别测定不同孵育时间(1、2、4、8h)TAL酶活性;Western blot检测TAL蛋白表达水平。磷酸酶消化法检测TAL活性变化与磷酸化的关系。结果:①人肝癌细胞株SMMC-7721中TAL活性在10%胎牛血清培养时明显高于1%胎牛血清,2、4、8h显著性差异(P<0.05)。②不同浓度(10%.1%)胎牛血清孵育2、4、8hTAL蛋白表达水平无显著性差异。③磷酸化消化后TAL活性,与消化前相比呈显著性下降。结论:人肝癌细胞株SMMC-7721中增加血清浓度明显提高TAL活性,酶活性变化与TAL蛋白表达水平无关,提示活性调节发生在蛋白翻译后修饰,其中磷酸化起重要作用。

Effect of phosphorylation on activity of transaldolase in human SMMC-7721 cell lines

Objectives:To investigate the effect of phosphorylation on activity of transaldolase in human SMMC-7721 cell lines.Methods:After cell synchronization, SMMC-7721 cell lines were treated with various doses(10%,1%)of fetal serum and were cultured at different time(1,2,4,8h).Then the activity of TAL was tested.By Western blot, expression of TAL protein was determined.By phospho-tase digestion, the relationship between phosphorylation and TAL activity was determined.Results:TAL activity in human SMMC-7721 cell lines cultured in 10% fetal serum was significantly higher than those cultured in 1% fetal serum at 2, 4, 8h(P<0.05).There was no significant difference of TAL protein expression among them.After phosphotase digestion, TAL activity in human SMMC-7721 cell lines decreased dramatically.Conclusion:Elevating the doses of fetal serum led to the vigorous raise of TAL activity.It is pointed out that the regulation of TAL activity mainly took place through post-translational modification, while there was no relation between TAL activity variation and protein expression, in which phosphorylation played an important role.