Table 1.
Boltzmann-fit parameters of the voltage-dependent BK channel activation in the absence and presence of the γ subunit and/or synthetic peptides
| Expression | Boltzmann fit parameters | ||
|---|---|---|---|
| V1/2 (mV) | z | n a | |
| BKα(TM-only) | 260 ± 2 | 1.43 ± 0.1 | 4 |
| BKα(TM-only) + γ1 | 269 ± 2 | 1.5 ± 0.16 | 4 |
| BKα | 172 ± 3 | 1.75 ± 0.09 | 9 |
| BKα-γ1 | 22 ± 3 | 1.75 ± 0.09 | 7 |
| BKα-γ2 | 61 ± 3 | 1.17 ± 0.07 | 8 |
| BKα-γ3 | 115 ± 2 | 1.36 ± 0.05 | 6 |
| BKα (10 µM Ca2+) | 17 ± 2 | 1.14 ± 0.06 | 10 |
| BKα-γ1 (10 µM Ca2+) | −71 ± 1 | 0.85 ± 0.02 | 4 |
| BKα-γ2 (10 µM Ca2+) | −62 ± 2 | 1.28 ± 0.12 | 7 |
| BKα-γ3 (10 µM Ca2+) | −17 ± 2 | 1.69 ± 0.15 | 5 |
| BKα(D362A/D367A/5D5N) | 163 ± 4 | 1.12 ± 0.11 | 3 |
| BKα(D362A/D367A/5D5N)-γ1 | 56 ± 5 (76%)b 160 ± 13 (24%)b |
1.29 ± 0.05 1.17 ± 0.12 |
5 |
| BKα(D362A/D367A/5D5N)-γ2 | 127 ± 13 | 0.73 ± 0.02 | 4 |
| BKα(D362A/D367A/5D5N)-γ3 | 174 ± 9 | 0.93 ± 0.16 | 6 |
| BKα(D362A/D367A) | 175 ± 2 | 1.07 ± 0.02 | 5 |
| BKα(D362A/D367A)-γ1 | 43 ± 4 | 1.37 ± 0.16 | 6 |
| BKα(D362A/D367A)-γ2 | 65 ± 3 | 1.08 ± 0.12 | 10 |
| BKα(D362A/D367A)-γ3 | 133 ± 2 | 1.58 ± 0.19 | 5 |
| BKα(5D5N) | 183 ± 2 | 1.32 ± 0.04 | 7 |
| BKα(5D5N)-γ1 | 85 ± 4 | 1.67 ± 0.73 | 5 |
| BKα(5D5N)-γ2 | 131 ± 2 | 0.91 ± 0.06 | 5 |
| BKα(5D5N)-γ3 | 182 ± 1 | 1.38 ± 0.11 | 5 |
| BKα + 20 µM γ1 peptide | 124 ± 3 | 1.39 ± 0.04 | 12 |
| BKα + 20 µM γ2 peptide | 135 ± 1 | 1.34 ± 0.17 | 7 |
| BKα + 20 µM γ3 peptide | 137 ± 1 | 1.14 ± 0.05 | 4 |
| BKα + 20 µM γ1-Δ4R peptide | 145 ± 1 | 1.19 ± 0.03 | 13 |
| BKα + 20 µM HIV-1 Tat peptide | 127 ± 2 | 1.49 ± 0.05 | 5 |
| BKα (whole-cell recording) | 188 ± 3 | 0.82 ± 0.02 | 5 |
| BKα + 20 µM HIV-1 Tat peptide (whole-cell recording) | 183± 7 | 0.85 ± 0.03 | 5 |
| BKα + 200 µM HIV-1 Tat peptide (whole-cell recording) | 162 ± 3 | 0.71 ± 0.03 | 5 |
| BKα + 20 µM HIV-1 Tat peptide (in pipette) | 179 ± 6 | 1.37 ± 0.06 | 5 |
| BKα (20 µM Ca2+) | 2 ± 4 | 1.53± 0.34 | 3 |
| BKα + 20 µM γ1 peptide (20 µM Ca2+) | −25 ± 4 | 1.66 ± 0.12 | 8 |
| BKα (1 mM Ca2+) | −60 ± 6 | 2.1 ± 0.12 | 3 |
| BKα + 20 µM γ1 peptide (1 mM Ca2+) | −72 ± 3 | 2.2 ± 0.2 | 3 |
| BKα(5D5N) + 20 µM γ1 peptide | 169 ± 3 | 1.32 ± 0.06 | 7 |
| BKα(5D5N) + 20 µM γ2 peptide | 165 ± 5 | 1.12 ± 0.09 | 4 |
| BKα(5D5N) + 20 µM γ3 peptide | 180 ± 3 | 1.25 ± 0.19 | 6 |
| BKα (1 M KMeSO3, 1,630 mOsm/kg) | 112 ± 3 | 1.13 ± 0.065 | 5 |
| BKα + 20 µM γ1 peptide (1 M KMeSO3, 1,630 mOsm/kg) | 122 ± 6 | 1.105 ± 0.18 | 5 |
| BKα (50 mM KMeSO3, 302 mOsm/kg) | 182 ± 3 | 1.13 ± 0.07 | 5 |
| BKα + 20 µM γ1 peptide (50 mM KMeSO3, 302 mOsm/kg) | 132 ± 4 | 1.16 ± 0.05 | 5 |
| BKα (140 mM KMeSO3, 1,650 mOsm/kg) | 172 ± 2 | 1.51 ± 0.28 | 4 |
| BKα + 20 µM γ1 peptide (140 mM KMeSO3, 1,650 mOsm/kg) | 132 ± 3 | 1.43 ± 0.06 | 4 |
| BKα-γ1 (1 M KMeSO3, 1,630 mOsm/kg) | −31 ± 5 | 0.95 ± 0.21 | 5 |
| BKα-γ1 + 20 µM γ1 peptide | −18 ± 5 | 1.32 ± 0.05 | 5 |
Unless indicated, recordings were done in the virtual absence of intracellular free Ca2+ and an inside-out configuration.
a
The number of recorded excised inside-out patches from different HEK293 cells.
b
Portion of the V1/2 component obtained by fitting with a double Boltzmann function.