蛋白质磷酸化和脱磷酸化对DNA拓扑异构酶Ⅰ活力调节的研究

Regulation of Topoisomerase Ⅰ from Normal Mouse Liver and H_(22a) Hepatoma Ascites Cells by Protein Phosphorylation and Dephosphorylation

本文以小鼠正常肝和H_(22a)腹水型肝癌细胞为材料,从中分离出纯度较高的拓扑异构酶Ⅰ和细胞质酪氨酸蛋白激酶(TPK)来研究磷酸化和脱磷酸化对拓扑异构酶Ⅰ活力的调节。结果表明TPK能活化拓扑异构酶Ⅰ。另外还发现PKA和碱性磷酸酶(CIP)能分别活化和抑制拓扑异构酶Ⅰ。

Tyrosine protein kinase and topoisomerase I were nearly homoge niously purified from both normal mouse liver and H_(22a) ascites cells. The purified enzymes were then used to study the possible phosphorylation and dephosphorylation of topisomerase Ⅰ. As a result, we found out that TPK can activate topoisomerase Ⅰ. Protein kinase A, a commercial product from rabbit muscle, can also activate topoisomerase Ⅰ. Calf intestinal alkaline phosphatase, also a commercial product, can inhibit the activity of topoisomerase Ⅰ.