Journal
ONCOGENE
Volume 23, Issue 23, Pages 4155-4165Publisher
NATURE PUBLISHING GROUP
DOI: 10.1038/sj.onc.1207566
Keywords
protein kinase CK2; phosphorylation; importin alpha/beta; nuclear import; cdc25C
Ask authors/readers for more resources
cdc25C is a phosphatase, which activates the mitosis-promoting factor cyclin B1/cdc2 by dephosphorylation, and thus triggers G(2)/M transition. The activity of cdc25C itself is controlled by phosphorylation of certain amino-acid residues, which among other things determines the subcellular localization of the enzyme. Here, we describe a new phosphorylation site at threonine 236 of cdc25C, which is phosphorylated by protein kinase CK2. This phosphorylation site is located near the nuclear localization signal ( amino acids 239 - 245). We demonstrate that cdc25C interacts with importin beta and the importin alpha/beta heterodimer but not with importin a. We further found that a cdc25C phosphorylation mutant where threonine 236 was replaced by aspartic acid as well as cdc25C phosphorylated by CK2 binds importin b or the importin alpha/beta heterodimer less efficiently than wild type or the corresponding alanine mutant. Furthermore, the cdc25C(T236D) shows a retarded uptake into the nucleus in a cell import assay. Inhibition of protein kinase CK2 enzyme activity in vivo resulted in an enhanced nuclear localization of cdc25C. Thus, phosphorylation of cdc25C at threonine 236 is an important signal for the retention of cdc25C in the cytoplasm.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available