Table 2.
Steady-state kinetic parameters for RGS17 and RGS4 GTPase activity
The GTPase activity of RGS17 and RGS4 was measured using a rate-altered Gαi1 variant (26, 45) in the presence or absence of saturating CaCl2 (100 μm). Data represents the mean of four independent experiments ±S.E. *, p = 0.018.
| kcat | Km | Vmax | kcat/Km | |
|---|---|---|---|---|
| min−1 | μm | % GTP hydrolysis | min−1/μm | |
| RGS17 + Gαi | 57.71 ± 2.94 | 1.49 ± 0.26* | 57.1 ± 2.94 | 38.7 ± 6.89 |
| RGS17 + Gαi + CaCl2 | 51.93 ± 2.18 | 0.56 ± 0.14 | 51.9 ± 2.12 | 92.9 ± 23.2 |
| RGS4 + Gαi | 61.78 ± 2.18 | 0.39 ± 0.08 | 61.8 ± 2.18 | 160.4 ± 34 |
| RGS4 + Gαi + CaCl2 | 60.38 ± 2.06 | 0.34 ± 0.07 | 60.4 ± 2.06 | 176 ± 38.1 |