Thömmes P, Reiter T, Knippers R
Biochemistry. 1986 Mar 25;25(6):1308-14. doi: 10.1021/bi00354a018.
Synchronously proliferating TC7 monkey and 3T3 mouse cells were pulse labeled with [35S]methionine. Radioactively labeled DNA polymerase alpha was immunoprecipitated with polymerase-specific monoclonal antibodies. The precipitated polypeptides were identified by gel electrophoresis and fluorography. The increase in DNA polymerase alpha activity during S phase was accompanied by an increased synthesis of the enzyme. Some DNA polymerase alpha was synthesized in growth-arrested TC7 cells whereas the synthesis of the large polymerase subunit in 3T3 cells was strictly coupled to the replicative phase of the cell cycle. We also found that DNA polymerase alpha was more prone to proteolysis in TC7 cells than in 3T3 cells. In 3T3 cells, a polymerase subunit with an apparent molecular weight of 186 000 was observed; this subunit was most probably associated with two smaller subunits of Mr 74 000 and 52 000. Synthesis of these three polymerase-associated polypeptides appeared to be regulated differently.
用[35S]甲硫氨酸对同步增殖的TC7猴细胞和3T3小鼠细胞进行脉冲标记。用聚合酶特异性单克隆抗体免疫沉淀放射性标记的DNA聚合酶α。通过凝胶电泳和荧光自显影鉴定沉淀的多肽。S期DNA聚合酶α活性的增加伴随着该酶合成的增加。在生长停滞的TC7细胞中合成了一些DNA聚合酶α，而3T3细胞中大型聚合酶亚基的合成与细胞周期的复制阶段严格相关。我们还发现，与3T3细胞相比，TC7细胞中的DNA聚合酶α更容易发生蛋白水解。在3T3细胞中，观察到一个表观分子量为186 000的聚合酶亚基；该亚基很可能与分子量为74 000和52 000的两个较小亚基相关。这三种与聚合酶相关的多肽的合成似乎受到不同的调节。
