Ferrari M, Lucchini G, Plevani P, Foiani M
Dipartimento di Genetica e di Biologia dei Microrganismi, Università degli Studi di Milano, Via Celoria 26, 20133 Milano, Italy.
J Biol Chem. 1996 Apr 12;271(15):8661-6. doi: 10.1074/jbc.271.15.8661.
The B subunit of the DNA polymerase (pol) alpha-primase complex executes an essential role at the initial stage of DNA replication in Saccharomyces cerevisiae and is phosphorylated in a cell cycle-dependent manner. In this report, we show that the four subunits of the yeast DNA polymerase alpha-primase complex are assembled throughout the cell cycle, and physical association between newly synthesized pol alpha (p180) and unphosphorylated B subunit (p86) occurs very rapidly. Therefore, B subunit phosphorylation does not appear to modulate p180.p86 interaction. Conversely, by depletion experiments and by using a yeast mutant strain, which produces a low and constitutive level of the p180 polypeptide, we found that formation of the p180.p86 subcomplex is required for B subunit phosphorylation.
DNA聚合酶（pol）α-引发酶复合物的B亚基在酿酒酵母DNA复制的起始阶段发挥着重要作用，并且以细胞周期依赖性方式被磷酸化。在本报告中，我们表明酵母DNA聚合酶α-引发酶复合物的四个亚基在整个细胞周期中组装，新合成的polα（p180）与未磷酸化的B亚基（p86）之间的物理结合非常迅速地发生。因此，B亚基磷酸化似乎不会调节p180.p86相互作用。相反，通过缺失实验以及使用产生低水平且组成型表达的p180多肽的酵母突变菌株，我们发现p180.p86亚复合物的形成是B亚基磷酸化所必需的。
