Table 3.
Effect of ATP/caffeine on [3H]ryanodine binding to Ca2+-coordinating residue mutants of RyR2
| EC50 (μm) |
p value | Basal activity (pmol/mg) |
p value | n number | |||
|---|---|---|---|---|---|---|---|
| Control | +ATP/Caff | Control | +ATP/Caff | ||||
| RyR2 WT | 0.21 ± 0.02 | 0.03 ± 0.003 | 0.0043 | 3.3 × 10−3 ± 0.7 × 10−3 | 53.9 × 10−3 ± 2.4 × 10−3 | 0.0003 | 3 |
| E3848A | >1.0 × 104 | >1.0 × 104 | -- | 28.0 × 10−3 ± 2.8 × 10−3 | 122.0 × 10−3 ± 6.1 × 10−3 | 0.0002 | 3 |
| E3848A/E3922A | -- | -- | -- | 51.1 × 10−3 ± 4.3 × 10−3 | 150.4 × 10−3 ± 23.2 × 10−3 | 0.0153 | 3 |
| H3850A | 0.78 ± 0.09 | 0.33 ± 0.12 | 0.0234 | 0.2 × 10−3 ± 0.4 × 10−3 | 3.6 × 10−3 ± 2.8 × 10−3 | 0.1685 | 3 |
| E3922A | >1.0 × 104 | >1.0 × 104 | -- | 8.2 × 10−3 ± 1.6 × 10−3 | 154.6 × 10−3 ± 22.1 × 10−3 | 0.0073 | 3 |
| Q3925A | 1.54 × 102 ± 0.26 × 102 | 0.22 × 102 ± 0.11 × 102 | 0.0059 | 0.002 × 10−3 ± 0.003 × 10−3 | 4.5 × 10−3 ± 2.7 × 10−3 | 0.1000 | 3 |
| T4931A | 0.43 ± 0.09 | 0.13 ± 0.04 | 0.0153 | 1.6 × 10−3 ± 0.5 × 10−3 | 37.9 × 10−3 ± 9.3 × 10−3 | 0.0210 | 3 |
Data are presented as mean ± S.D. The significance of difference in EC50 and basal activity with and without 3 mm ATP/3 mm caffeine was assessed by two-tailed Student's t tests. A p value <0.05 was considered statistically significant.