Stec J, Busbee D
Department of Anatomy, College of Veterinary Medicine, Texas A&M University, College Station 77843.
Biochem Biophys Res Commun. 1988 Jun 30;153(3):1324-32. doi: 10.1016/s0006-291x(88)81373-1.
DNA polymerase alpha isolated from adult-derived lymphocytes was separated into isozyme forms with low (A1) and high (A2) specific activity. In quiescent lymphocytes only A1 was detected, while mitogen-stimulated lymphocytes contained both A1 and A2 enzyme. Polymerase alpha A1, but not A2, interacted with phosphatidylinositol, ATP, and phosphatidylinositol kinase to yield an activated enzyme with increased affinity of binding to DNA. Mitogen-stimulated lymphocytes showed increased enzyme protein and total activity for both A1 and A2, but, when pre-treated with cycloheximide, exhibited an apparent increase in A2 specific activity with no increase in activity for A1 polymerase. These data suggest that mitogen stimulation of lymphocytes increased total DNA polymerase alpha activity by the phosphoinositide-related activation of polymerase alpha A1 to an A2-like form and by initiating de-novo synthesis of polymerase alpha A2.
从成年来源的淋巴细胞中分离出的DNA聚合酶α被分为具有低（A1）和高（A2）比活性的同工酶形式。在静止淋巴细胞中仅检测到A1，而有丝分裂原刺激的淋巴细胞同时含有A1和A2酶。聚合酶α A1而非A2与磷脂酰肌醇、ATP和磷脂酰肌醇激酶相互作用，产生一种对DNA结合亲和力增加的活化酶。有丝分裂原刺激的淋巴细胞显示A1和A2的酶蛋白和总活性均增加，但是，当用环己酰亚胺预处理时，A2比活性明显增加，而A1聚合酶活性没有增加。这些数据表明，有丝分裂原刺激淋巴细胞通过磷脂酰肌醇相关的将聚合酶α A1激活为A2样形式以及启动聚合酶α A2的从头合成来增加总DNA聚合酶α活性。
