Table 3.
Steady-state kinetic data for phosphorylated (−λ) and dephosphorylated (+λ) lipin PBD mutants
The data were generated from assays using PC/PA or PC/PE/PA liposomes containing 10 mol % PA, the indicated mol % PE, and additional PC to bring the combined concentration of phospholipids to 100 mol %. The specific activity was measured as Vmax/mg protein. Student's t test was used to analyze statistical significance.
| PE | Kmapp | Kcat | Kcat/Kmapp | |
|---|---|---|---|---|
| mol % | μm | s−1 | μm−1 s−1 | |
| Lipin 1 (3PBD) | ||||
| −λ | 0 | 211 ± 170 | 0.76 ± 0.23 | 0.003 |
| −λ | 30 | 191 ± 88 | 1.66 ± 0.17 | 0.008 |
| +λ | 0 | 170 ± 99 | 0.64 ± 0.06 | 0.004 |
| +λ | 30 | 146 ± 54 | 1.64 ± 0.34 | 0.011 |
| Lipin 3 (1PBD) | ||||
| −λ | 0 | 120 ± 69 | 0.67 ± 0.09 | 0.005 |
| −λ | 30 | 117 ± 31 | 0.92 ± 0.05 | 0.007 |
| +λ | 0 | 107 ± 40 | 0.78 ± 0.19 | 0.007 |
| +λ | 30 | 155 ± 38 | 2.02 ± 0.26 | 0.014 |