REVERSIBLE PHOSPHORYLATION CONTROLS THE ACTIVITY OF CYCLOSOME-ASSOCIATED CYCLIN-UBIQUITIN LIGASE
REVERSIBLE PHOSPHORYLATION CONTROLS THE ACTIVITY OF CYCLOSOME-ASSOCIATED CYCLIN-UBIQUITIN LIGASE
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DOI：
10.1073/pnas.92.20.9303
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发表时间：
1995-09-26
影响因子：
11.1
通讯作者：
HERSHKO, A
中科院分区：
文献类型：
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作者：
LAHAVBARATZ, S;SUDAKIN, V;HERSHKO, A
细胞周期蛋白B/cdc2。它既负责驱动细胞进入有丝分裂，也负责在有丝分裂结束时激活泛素依赖的有丝分裂周期蛋白的降解，这是完成有丝分裂并进入下一个细胞周期间期所必需的事件。以前对快速分裂的文蛤胚胎的无细胞提取物的工作已经确定了有丝分裂周期蛋白泛素化所需的两种特定成分：E(2)-C，一种细胞周期蛋白选择性泛素载体蛋白，在细胞周期中具有结构性活性；E(3)-C，一种周期蛋白选择性泛素连接酶，作为约1500 kDa复合体的一部分进行纯化，称为环体，仅在有丝分裂结束时活性。我们已经将环体从其最终的上游激活剂cdc2中分离出来。有丝分裂的活性形式的环体可以通过与部分纯化的内源性冈田酸敏感的磷酸酶孵育而失活；加入cdc2可以在一段滞后之后恢复环体的活性，这一滞后复制了以前在完整细胞和粗提物中看到的。这些结果表明，细胞周期蛋白-泛素连接酶的活性受环体复合体的可逆磷酸化控制。
Cyclin B/cdc2. is responsible both for driving cells into mitosis and for activating the ubiquitin-dependent degradation of mitotic cyclins near the end of mitosis, an event required for the completion of mitosis and entry into interphase of the next cell cycle. Previous work with cell-free extracts of rapidly dividing clam embryos has identified two specific components required for the ubiquitination of mitotic cyclins: E(2)-C, a cyclin-selective ubiquitin carrier protein that is constitutively active during the cell cycle, and E(3)-C, a cyclin-selective ubiquitin ligase that purifies as part of a approximate to 1500-kDa complex, termed the cyclosome, and which is active only near the end of mitosis. Were, we have separated the cyclosome from its ultimate upstream activator, cdc2. The mitotic, active form of the cyclosome can be inactivated by incubation with a partially purified, endogenous okadaic acid-sensitive phosphatase; addition of cdc2 restores activity to the cyclosome after a lag that reproduces that seen previously in intact cells and in crude extracts. These results demonstrate that activity of cyclin-ubiquitin ligase is controlled by reversible phosphorylation of the cyclosome complex.