Recombinant Human CDC25B (aa 377-566) Protein, CF

Cell Division Cycle 25B (Cdc25B) phosphatase removes inorganic phosphate groups covalently attached to tyrosine, serine and threonine residues in proteins (1). Breast cancer patients bearing tumors containing high levels of Cdc25B have been found to have a greater incidence of aggressive, high‑grade tumors than those with low Cdc25B levels (2). In cells, the levels of Cdc25B activity are highest during the G2/M transition of the cell cycle, where it is suspected to be involved in “checkpoint” control of cell cycle progression (3). Overexpression of Cdc25B reduces the G2/M cell cycle block caused by ionizing radiation (4). Although activated by phosphorylation, Ser323 phosphorylation causes the enzyme to bind the protein 14-3-3, preventing substrate access to the catalytic site (5). One of the major substrates of Cdc25B is Cdc2, a kinase that is activated by dephosphorylation (6). The recombinant protein is truncated to remove the N-terminal regulatory domains and is fully active.