Table 3.
Comparison of PP1 inhibitory activities of various I-1 species
| Inhibitor | IC50, nM |
|---|---|
| I-1 | No inhibition |
| A kinase-phosphorylated I-1 | 7.5 ± 0.49 |
| NCLK-phosphorylated I-1 | 9.5 ± 0.93 |
| NCLK/A kinase-phosphorylated I-1 | 4.8 ± 0.18 |
| I-1(T35A) | No inhibition |
| NCLK-phosphorylated I-1(T35A) | 13.8 ± 1.5 |
| GST-I-1 | No inhibition |
| A kinase-phosphorylated GST-I-1 | 55 ± 4 |
| NCLK-phosphorylated GST-I-1 | 74 ± 7 |
| GST-I-1(T35A) | No inhibition |
| NCLK-phosphorylated GST-I-1(T35A) | 149 ± 12 |
PP1 activity in the presence of various concentrations of indicated I-1 species was monitored and plotted as in Fig. 3. IC50 (concentration of inhibitor required for half-maximal inhibition) was determined from the plot. Values are mean of three independent determinations.