TABLE 2.
Ca2+ conductance expressed by domain chimeras and heptad repeat mutants in β1 KO myotubes
|
G-V
|
|||
|---|---|---|---|
| Gmax (pS/pF) | V1/2 (mV) | k (mV) | |
| WT β1a | 195 ± 23 (10) | 15 ± 2 | 4.5 ± 0.6 |
| WT β2a | 184 ± 36 (6) | 11 ± 1 | 5.1 ± 0.3 |
| β2a(D1–D3)/β1a(D4, D5) | 223 ± 17 (19) | 12 ± 1 | 4.2 ± 0.4 |
| β1a(D1–D3)/β2a(D4, D5) | 63 ± 6* (20) | 16 ± 1 | 4.9 ± 0.3 |
| β2a(D1–D4)/β1aD5 | 158 ± 31 (9) | 7 ± 2 | 4.4 ± 0.4 |
| β1a(D1–D4)/β2aD5 | 48 ± 12* (7) | 21 ± 3 | 6.1 ± 0.8 |
| β2a(D1–D4)/β2aD5/β1aD5 | 193 ± 38 (8) | 17 ± 2 | 4.9 ± 0.6 |
| β2a(D1–D4)/β1aD5/β2aD5 | 174 ± 28 (7) | 11 ± 2 | 3.1 ± 0.4 |
| β1a(D1–D4)/β1aD5/β2aD5 | 180 ± 20 (7) | 18 ± 2 | 5.4 ± 0.6 |
| β1a(D1–D4)/β2aD5/β1aD5 | 71 ± 14 (6) | 20 ± 2 | 5.0 ± 0.3 |
| D5ALA (L478A, V485A, V492A) | 121 ± 18 (8) | 23 ± 4 | 4.4 ± 0.3 |
| D5ALAc (S481A, L488A, S495A) | 134 ± 16 (8) | 23 ± 2 | 5.0 ± 0.2 |
| Nontransfected β1 KO | 20 ± 5* (10) | 20.3 ± 7 | 14 ± 2.2* |
Mean ± SEM of Boltzmann parameters fitted to each cell with number of cells in parenthesis. Gmax, V1/2, and k are parameters of the Boltzmann fit to each cell with Eq. 1.
*
Parameters in each column compared to WT β1a with one-way ANOVA significance p < 0.05. Data for WT β1a and WT β2a are from Sheridan et al. (2003b).