Proteasome-dependent degradation of human CDC25B phosphatase
Proteasome-dependent degradation of human CDC25B phosphatase
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DOI：
10.1023/a:1006912105352
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发表时间：
1999-04-01
影响因子：
2.8
通讯作者：
Baldin, V
中科院分区：
文献类型：
--
作者：
Cans, C;Ducommun, B;Baldin, V
CDC 25双特异性磷酸酶是一种通用的细胞周期调节剂。这种酶从酵母到人类的进化保守性证明了它在细胞周期蛋白依赖性激酶（CDK）活性控制中的主要作用，CDK是细胞周期机制的中央调节器。CDC 25磷酸酶既能使CDK去磷酸化又能激活CDK。已经鉴定了三种人CDC 25。CDC 25 A参与G1/S期的调控，而CDC 25 C在G2/M期参与CDK 1-cyclin B的激活。然而，CDC 25 B的确切功能仍然难以捉摸。我们已经发现，CDC 25 B是由蛋白酶体途径在体外和体内降解。这种降解依赖于CDK 1-细胞周期蛋白A复合物的磷酸化，而不依赖于CDK 1-细胞周期蛋白B。再加上其他人在酵母和哺乳动物中的观察，我们的研究结果表明，CDC 25 B可能作为一个“有丝分裂启动器”，在被降解之前触发自动扩增环的激活。
The CDC25 dual specificity phosphatase is a universal cell cycle regulator. The evolutionary conservation of this enzyme from yeast to man bears witness to its major role in the control of cyclin-dependent kinases (CDK) activity that are central regulators of the cell cycle machinery. CDC25 phosphatase both dephosphorylates and activates CDKs. Three human CDC25s have been identified. CDC25A is involved in the control of G1/S, and CDC25C at G2/M throught the activation of CDK1-cyclin B. The exact function of CDC25B however remains elusive. We have found that CDC25B is degraded by the proteasome pathway in vitro and in vivo. This degradation is dependent upon phosphorylation by the CDK1-cyclin A complex, but not by CDK1-cyclin B. Together with the observations of others made in yeast and mammals, our results suggest that CDC25B might act as a 'mitotic starter' triggering the activation of an auto-amplification loop before being degraded.