Phosphorylation of replication protein A: a role for cdc2 kinase in G1/S regulation.
Phosphorylation of replication protein A: a role for cdc2 kinase in G1/S regulation.
复制标题
复制蛋白 A 的磷酸化：cdc2 激酶在 G1/S 调节中的作用。
DOI：
10.1101/sqb.1991.056.01.038
复制
发表时间：
1991
期刊：
影响因子：
--
通讯作者：
Stillman,B
中科院分区：
文献类型：
--
作者：
Dutta,A;Din,S;Brill,SJ;Stillman,B
图1。完全体外复制所需的动物细胞的纯化部分，来自DNA复制的SV40来源(Tsurimoto等人)。1990年)。在复制结束时，需要拓扑异构酶II来分解这两个子分子。所有这些细胞复制因子的鉴定使我们能够解决人类DNA复制的细胞周期控制问题。在缺乏在细胞复制起点执行类似于T抗原功能的蛋白质的情况下，我们将注意力集中在形成预起始复合体RPA所必需的细胞蛋白质上。人细胞RPA是由70kD、34kD和13kD三种多肽组成的复合体。使用针对RPA的单抗表明，RPA的量在细胞周期中是不变的，并且蛋白质在Gt中不被磷酸化(Din等人。1990年)。然而，随着细胞进入S期，34-kD亚基在丝氨酸残基上被磷酸化，随后在M期去磷酸化。如下所述，当细胞进入S期时，酿酒酵母的RPA也在中间亚基上被磷酸化。磷酸化是调节几种蛋白质活性的一种常见机制。因此，RPA在真核生物中的磷酸化，如人类和酵母，恰好在细胞周期中DNA复制装置被激活的时间，表明磷酸化参与了G1/S的调控。我们在下面介绍我们在这个问题上的一些最新发现。
Figure 1. Purified fractions from animal ceils required for complete replication in vitro from an SV40 origin of DNA replication (Tsurimoto et al. 1990). fork, and topoisomerase II is required to resolve the two daughter molecules at the end of replication. Identification of all these cellular replication factors allowed us to address the question of cell cycle control of human DNA repIication. In the absence of proteins that perform a function similar to T antigen at cellular origins of replication, we have focused our attention on the cellular protein essential for the formation of the preinitiation complex, RPA. RPA from human cells is a complex of three polypeptides of 70 kD, 34 kD, and 13 kD. The use of monoclonal antibodies made against RPA showed that the amount of RPA was invariant through the cell cycle and that the protein was not phosphorylated in G t (Din et al. 1990). The 34-kD subunit, however, was phosphorylated on serine residues as the cells entered S phase and subsequently dephosphorylated in M phase. As discussed below, RPA from Saccharomyces cerevisiae is also phosphorylated on the middle subunit as the cells enter S phase. Phosphorylation is a common mechanism by which the activities of several proteins are regulated. Hence, phosphorylation of RPA in eukaryotes as diverse as humans and yeast, at exactly the time when the DNA replication apparatus is activated in the cell cycle, suggests that the phosphorylation is involved in G1/S control. We present some of our recent findings on this issue below.