DNA Replication Factor A (RPA) associates with the pre-replicative complex at the origin

After pre-RC assembly and Cdc45 association with the origin of replication, Replication Protein A (RPA) also associates with chromatin. RPA is a heterotrimeric complex containing p70, p34, and p11 subunits, and also is required for DNA recombination and DNA repair. The p70 subunit of RPA binds to the primase subunits of Pol alpha:primase. The p70 and p34 subunits of RPA are phosphorylated in a cell cycle-dependent manner. RPA is a single-strand DNA (ssDNA) binding protein and its association with chromatin at this stage suggests that DNA is partially unwound. This suggestion has been confirmed by detection of ssDNA in budding yeast origins of replication using chemical methods.

在预-RC 组装以及 Cdc45 与复制起点结合之后，复制蛋白 A (RPA) 还与染色质相结合。RPA 是一种由 p70、p34 和 p11 亚基组成的异源三聚体复合物，且对于 DNA 重排和 DNA 修复亦不可或缺。RPA 的 p70 亚基与 Pol alpha:primase 的引物酶亚基结合。RPA 的 p70 和 p34 亚基以细胞周期依赖性方式进行磷酸化。RPA 是一种单链 DNA (ssDNA) 结合蛋白，其在此阶段与染色质的结合暗示 DNA 部分解旋。此推测已通过在芽殖酵母复制起点检测到单链 DNA 的化学方法得到证实。