Phosphorylation at serine 75 is required for UV-mediated degradation of human Cdc25A phosphatase at the S-phase checkpoint
I Hassepass, R Voit, I Hoffmann - Journal of Biological Chemistry, 2003 - ASBMB
The human Cdc25A phosphatase plays a pivotal role at the G 1/S transition by activating
cyclin E and A/Cdk2 complexes through dephosphorylation. In response to ionizing
radiation, Cdc25A is phosphorylated by both Chk1 and Chk2 on Ser-123. This in turn leads
to ubiquitylation and rapid degradation of Cdc25A by the proteasome resulting in cell cycle
arrest. We found that in response to UV irradiation, Cdc25A is phosphorylated at a different
serine residue, Ser-75. Significantly, Cdc25A mutants carrying alanine instead of either Ser …
cyclin E and A/Cdk2 complexes through dephosphorylation. In response to ionizing
radiation, Cdc25A is phosphorylated by both Chk1 and Chk2 on Ser-123. This in turn leads
to ubiquitylation and rapid degradation of Cdc25A by the proteasome resulting in cell cycle
arrest. We found that in response to UV irradiation, Cdc25A is phosphorylated at a different
serine residue, Ser-75. Significantly, Cdc25A mutants carrying alanine instead of either Ser …
