Busch Corinna, Barton Olivia, Morgenstern Eberhard, Götz Claudia, Günther Jürgen, Noll Andreas, Montenarh Mathias
Medizinische Biochemie und Molekularbiologie, Universität des Saarlandes, Gebäude 44, 66424 Homburg, Germany.
Int J Biochem Cell Biol. 2007;39(9):1707-13. doi: 10.1016/j.biocel.2007.04.022. Epub 2007 May 3.
cdc25C is a phosphatase which regulates the activity of the mitosis promoting factor cyclin B/cdk1 by dephosphorylation, thus triggering G(2)/M transition. The activity and the sub-cellular localisation of cdc25C are regulated by phosphorylation. It is well accepted that cdc25C has to enter the nucleus to activate the cyclin B/cdk1 complex at G(2)/M transition. Here, we will show that cdc25C is located in the cytoplasm at defined dense structures, which according to immunofluorescence analysis, electron microscopy as well as biochemical subfractionation, are proven to be the centrosomes. Since cyclin B and cdk1 are also located at the centrosomes, this subfraction of cdc25C might participate in the control of the onset of mitosis suggesting a further role for cdc25C at the centrosomes.
细胞周期蛋白依赖性激酶25C（cdc25C）是一种磷酸酶，它通过去磷酸化作用调节有丝分裂促进因子细胞周期蛋白B/细胞周期蛋白依赖性激酶1（cyclin B/cdk1）的活性，从而触发G2/M期转换。cdc25C的活性和亚细胞定位受磷酸化作用调控。人们普遍认为，cdc25C必须进入细胞核才能在G2/M期转换时激活细胞周期蛋白B/cdk1复合物。在此，我们将证明cdc25C定位于细胞质中特定的致密结构，根据免疫荧光分析、电子显微镜以及生化亚组分分离结果，这些结构被证实为中心体。由于细胞周期蛋白B和cdk1也定位于中心体，cdc25C的这一亚组分可能参与有丝分裂起始的调控，提示cdc25C在中心体处具有进一步的作用。
