Alternative splicing in the regulatory region of the human phosphatases CDC25A and CDC25C

CDC25 phosphatases play key roles in cell proliferation by activating tell cycle-specific cyclin-dependent kinases (CDKs). We identified four new spli ce variants in the amino-terminal regulatory region of human cdc25C and one in cdc25A. All variants except one retain an intact catalytic domain. Alte rnative splicing results in loss of phosphorylation sites for kinases like CDK and the calcium/calmodulin-dependent kinase II (CaMKII), which influenc e CDC25 activity and compartmental localization. In NT2 teratocarcinoma cel ls, induced for nerve cell differentiation, the smaller sized variant of cd c25C aas upregulated. At the protein level both phosphorylation state and i soform distribution differed between cell lines and cell cycle phases.