An Active C-Terminally Truncated Form of Ca2+/Calmodulin-Dependent Protein Kinase Phosphatase-N (CaMKP-N/PPM1E)
Figure 8
The reversible inactivation of hCaMKP-N(1–559) by H2O2. (a) hCaMKP-N(1–559) (245 μg/mL) was incubated on ice for 30 min in 25 mM Tris-HCl (pH 7.5) with or without the indicated concentrations of H2O2, and then the phosphatase activities were determined using pp10 as the substrate. (b) hCaMKP-N(1–559) (245 μg/mL) was incubated on ice for 30 min in 25 mM Tris-HCl (pH 7.5) with 5 mM H2O2, and then DTT (50 mM) was added for incubation on ice for an additional 30 min. Thereafter, the phosphatase activity was determined using pp10 as the substrate. As a comparison, the phosphatase activity without DTT treatment is also presented (5 mM H2O2). The DTT treatment itself had no significant effects on the activity of hCaMKP-N(1–559) in the control (50 mM DTT). The results are expressed as a percentage of the control activity (none), which was determined after incubation without any compounds (H2O2 or DTT) added. The data represent the average of three independent experiments ± S.D.
