Determination of initiation of DNA replication before and after nuclear formation in Xenopus egg cell free extracts.
Determination of initiation of DNA replication before and after nuclear formation in Xenopus egg cell free extracts.
复制标题
DOI：
10.1083/jcb.123.6.1321
复制
发表时间：
1993-12
期刊：
影响因子：
--
通讯作者：
Takisawa H
中科院分区：
文献类型：
--
作者：
Kubota Y;Takisawa H
在卵活化之前和之后制备的爪蟾卵提取物分别保留M-和S-相比活性。星形孢菌素是一种有效的蛋白激酶抑制剂，可将M期提取物转化为间期样提取物，加入精子DNA后，这些提取物能够形成细胞核。在星形孢菌素处理的M期提取物中形成的核不能复制DNA，并且它们在加入S期提取物后不能启动复制。此外，当在添加DNA之前将星形孢菌素处理的M期提取物过量添加到星形孢菌素处理的S期提取物中时，复制被抑制。膜耗尽的S期提取物既不支持核形成也不支持复制;然而，精子DNA与这些提取物的预孵育允许它们在添加过量的星形孢菌素处理的M期提取物后形成具有复制能力的核。这些结果表明，在S期提取物中的阳性因子决定了核形成前DNA复制的启动，尽管这些因子不能在核形成后启动复制。
Xenopus egg extracts prepared before and after egg activation retain M- and S-phase specific activity, respectively. Staurosporine, a potent inhibitor of protein kinase, converted M-phase extracts into interphase- like extracts that were capable of forming nuclei upon the addition of sperm DNA. The nuclei formed in the staurosporine treated M-phase extract were incapable of replicating DNA, and they were unable to initiate replication upon the addition of S-phase extracts. Furthermore, replication was inhibited when the staurosporine-treated M- phase extract was added in excess to the staurosporine-treated S-phase extract before the addition of DNA. The membrane-depleted S-phase extract supported neither nuclear formation nor replication; however, preincubation of sperm DNA with these extracts allowed them to form replication-competent nuclei upon the addition of excess staurosporine- treated M-phase extract. These results demonstrate that positive factors in the S-phase extracts determined the initiation of DNA replication before nuclear formation, although these factors were unable to initiate replication after nuclear formation.