Comparative analysis of two murine CDC25B isoforms

Abstract

CDC25B phosphatase plays a pivotal role in the cell cycle process by dephosphorylating and activating the CDC2 kinase of maturation-promoting factor (MPF). In mice, two transcripts of Cdc25B are generated by the alternative splicing of one gene. We compared the properties of these two forms of CDC25B. When the expression pattern of Cdc25B was examined using RT-PCR, both forms were detected in almost all mouse tissues tested. The expression of two forms of the CDC25B protein in various mouse tissues was confirmed using Western blotting with generated isoform specific antibodies. CDC25B1 tends to accumulate more in the cytosol than CDC25B2 does, and they have different binding capacity for 14-3-3 proteins. CDC25B1 was more effective in dephosphorylating in vitro substrate para-nitrophenyl phosphate and showed higher activity in the modified histone H1 kinase assay than CDC25B2. These results suggest that the two forms of CDC25B play different roles in cell cycle regulation.