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现已证明增殖细胞核抗原(PCNA)和周期素完全相同,此蛋白质存在于正常增殖细胞和转化细胞中,周期素/PCNA的合成受细胞周期的调节, DNA复制期它的浓度迅速增高,而静息期细胞仅表达很少量的周期素/PCNA。最近有报告发现周期素/PCNA为SV_(40)DNA体外复制所必需而且周期素/PCNA本身就是一种DNA多聚酶δ的铺助蛋白。该辅助蛋白能增强DNA多聚酶δ利用模板的能力,间接说明周期素/PCNA在DNA合成中起重要作用。
It has been demonstrated that proliferating cell nuclear antigen (PCNA) is exactly the same as cyclin, which is present in normal proliferating cells and transformed cells. The synthesis of cyclin / PCNA is regulated by the cell cycle and its concentration is rapidly increased during DNA replication. Perinatal cells express only a small amount of cyclin / PCNA. Recently, it has been reported that cyclin / PCNA is required for the in vitro replication of SV_ (40) DNA and that cyclin / PCNA itself is a chelator of DNA polymerase δ. This accessory protein enhances the ability of DNA polymerase delta to utilize the template, indirectly suggesting that cyclin / PCNA play an important role in DNA synthesis.