Table 1.
Parameters of the voltage dependence of steady-state activation (left) or inactivation (right) of Cav1.3L or Cav1.342A LTCCs measured with α2δ1 and different β subunits (β3, β2a, β2e) in the presence or absence of RIM2α and/or RBP2
| Construct | Activation | Inactivation | ||||||
|---|---|---|---|---|---|---|---|---|
| V0.5,act [mV] | k | Act thresh [mV] | n | V0.5,inact [mV] | kinact | Plateau [%] | ninact | |
| Cav1.3L/β3 | − 11.5 ± 0.8 | 7.8 ± 0.1 | − 41.3 ± 0.9 | 20 | − 27.6 ± 2.2 | 6.0 ± 0.3 | 27.9 ± 3.4 | 9 |
| + RIM2α | − 14.4 ± 0.9 | 8.1 ± 0.1 | − 45.8 ± 0.7*** | 19 | − 28.4 ± 1.7 | 6.3 ± 0.5 | 30.6 ± 2.8 | 11 |
| + RBP2 | − 14.8 ± 0.9* | 7.6 ± 0.2 | − 43.2 ± 0.5 | 21 | − 25.6 ± 2.0 | 5.5 ± 0.2 | 38.1 ± 3.5 | 14 |
| + RIM2α/RBP2 | − 14.1 ± 0.9 | 8.1 ± 0.2 | − 44.5 ± 0.6** | 21 | − 23.5 ± 1.3 | 7.6 ± 0.5 | 50.8 ± 3.1***,### | 17 |
| Cav1.342A/β3 | − 19.0 ± 0.7 | 6.9 ± 0.2 | − 44.5 ± 0.6 | 21 | − 30.6 ± 1.3 | 4.8 ± 0.2 | 27.4 ± 2.9 | 14 |
| + RIM2α | − 23.1 ± 0.5*** | 6.6 ± 0.1 | − 47.4 ± 0.6** | 18 | − 30.6 ± 0.6 | 5.1 ± 0.3 | 44.1 ± 2.8*** | 11 |
| + RBP2 | − 20.7 ± 0.9 | 6.5 ± 0.2 | − 44.4 ± 0.6 | 12 | − 29.2 ± 1.4 | 5.1 ± 0.5 | 28.6 ± 2.7 | 9 |
| + RIM2α/RBP2 | − 21.8 ± 0.9* | 6.8 ± 0.1 | − 47.0 ± 1.0 | 13 | − 30.9 ± 1.6 | 5.6 ± 0.5 | 36.4 ± 3.9 | 9 |
| Cav1.3L/β2a | − 7.2 ± 1.4 | 9.4 ± 0.1 | − 44.1 ± 1.1 | 17 | − 16.5 ± 2.3 | 13.0 ± 0.8 | 47.6 ± 5.6 | 9 |
| + RIM2α | − 9.2 ± 1.8 | 9.1 ± 0.2 | − 44.4 ± 1.4 | 9 | − 17.3 ± 4.3 | 11.3 ± 1.2 | 45.1 ± 4.6 | 7 |
| + RBP2 | − 11.0 ± 1.2 | 9.1 ± 0.2 | − 46.2 ± 1.3 | 10 | − 18.8 ± 1.9 | 11.1 ± 0.7 | 51.8 ± 2.5 | 6 |
| + RIM2α/RBP2 | − 12.2 ± 1.0* | 9.2 ± 0.2 | − 48.0 ± 0.8* | 17 | − 20.0 ± 2.2 | 10.9 ± 0.5 | 52.4 ± 3.6 | 10 |
| Cav1.3L/β2e | − 7.5 ± 2.1 | 8.8 ± 0.3 | − 41.9 ± 1.2 | 11 | − 24.0 ± 2.8 | 7.5 ± 0.8 | 25.6 ± 4.3 | 7 |
| + RIM2α | − 13.5 ± 1.5* | 8.9 ± 0.2 | − 47.8 ± 1.0** | 11 | − 22.4 ± 1.6 | 9.0 ± 0.4 | 42.4 ± 3.3* | 8 |
| + RBP2 | − 7.8 ± 0.8 | 9.1 ± 0.2 | − 43.0 ± 1.0 | 11 | − 21.1 ± 2.0 | 9.7 ± 1.0 | 32.2 ± 7.2 | 6 |
| + RIM2α/RBP2 | − 15.6 ± 1.4** | 8.5 ± 0.1 | − 47.7 ± 1.0** | 15 | − 24.6 ± 2.5 | 8.5 ± 0.7 | 42.6 ± 2.5* | 10 |
| Cav1.342A/β2a | − 22.2 ± 1.2 | 7.5 ± 0.2 | − 50.2 ± 1.1 | 14 | − 32.4 ± 1.8 | 6.7 ± 0.6 | 60.9 ± 3.5 | 8 |
| + RIM2α | − 23.2 ± 0.6 | 7.3 ± 0.3 | − 50.2 ± 1.4 | 14 | − 35.0 ± 1.4 | 5.4 ± 0.3 | 49.1 ± 4.3 | 10 |
| + RBP2 | − 21.9 ± 1.1 | 7.0 ± 0.1 | − 47.5 ± 1.3 | 13 | − 32.2 ± 1.7 | 5.8 ± 0.5 | 56.0 ± 4.3 | 11 |
| + RIM2α/RBP2 | − 23.3 ± 0.8 | 7.3 ± 0.2 | − 50.5 ± 1.1 | 16 | − 34.0 ± 1.6 | 6.5 ± 0.9 | 45.8 ± 3.0* | 10 |
Data are given as means ± SEM. Statistical significance was determined by one-way ANOVA with Bonferroni’s multiple comparison post hoc test as indicated in the table. Versus control (Cav1.3 without RIM2α and/or RBP2): ***p < 0.001; **p < 0.01; *p < 0.05; RIM2α versus RIM2α/RBP2: ###p < 0.001
V0.5,act, voltage of half-maximal activation; k, slope factor; act thresh, activation threshold (voltage where 5% of maximal IBa is reached); V0.5,inact, voltage of half-maximal inactivation; kinact, inactivation slope factor