Identification and characterization of a human protein kinase related to budding yeast Cdc7p
Identification and characterization of a human protein kinase related to budding yeast Cdc7p
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DOI：
10.1073/pnas.94.26.14320
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发表时间：
1997-12-23
影响因子：
11.1
通讯作者：
Hunter, T
中科院分区：
文献类型：
--
作者：
Jiang, W;Hunter, T
Cdc7p 蛋白激酶对于酿酒酵母细胞分裂周期中的 G(1)/S 转变和 DNA 复制启动至关重要，Cdc7p 似乎是一种进化上保守的蛋白，因为已从粟酒裂殖酵母中分离出同源物 Hsk1。在这里，我们报告了人类 cDNA HsCdc7 的分离，其产物在序列上与 Cdc7p 和 Hsk1 密切相关。 HsCdc7 cDNA 编码 574 个氨基酸的蛋白质，预计大小为 64 kDa，HsCdc7 包含所有蛋白质丝氨酸/苏氨酸激酶共有的保守子结构域以及 Cdc7p 和 Hsk1 特征的三个“激酶插入片段”。来自细胞裂解物的 HsCdc7 免疫复合物能够在体外磷酸化组蛋白 H1，间接免疫荧光染色证明 HsCdc7 蛋白主要定位于细胞核，尽管 HsCdc7 的表达水平在整个细胞周期中似乎恒定，但 HsCdc7 的蛋白激酶活性在细胞周期的 S 期期间与 Cdk2 大约同时增加，这些结果以及 Cdc7p 在酵母中的功能，表明 HsCdc7 可能磷酸化调节哺乳动物细胞中 G(1)/S 相变和/或 DNA 复制的关键底物。
The Cdc7p protein kinase is essential for the G(1)/S transition and initiation of DNA replication during the cell division cycle in Saccharomyces cerevisiae, Cdc7p appears to be an evolutionarily conserved protein, since a homolog Hsk1 has been isolated from Schizosaccharomyces pombe. Here, we report the isolation of a human cDNA, HsCdc7, whose product is closely related in sequence to Cdc7p and Hsk1. The HsCdc7 cDNA encodes a protein of 574 amino acids with predicted size of 64 kDa, HsCdc7 contains the conserved subdomains common to all protein-serine/threonine kinases and three "kinase inserts" that are characteristic of Cdc7p and Hsk1. Immune complexes of HsCdc7 from cell lysates were able to phosphorylate histone H1 in vitro, Indirect immunofluorescence staining demonstrated that HsCdc7 protein was predominantly localized in the nucleus, Although the expression levels of HsCdc7 appeared to be constant throughout the cell cycle, the protein kinase activity of HsCdc7 increased during S phase of the cell cycle at approximately the same time as that of Cdk2, These results, together with the functions of Cdc7p in yeast, suggest that HsCdc7 may phosphorylate critical substrate(s) that regulate the G(1)/S phase transition and/or DNA replication in mammalian cells.