Parameters for a two-resistor modela of the conduction pathway of E321G/E324G BK channels, unless indicated
| Parameterb | gT | R1 | R2 | R1/R2 | W | L | D | Wwtc | Dwtc |
| pS | GΩ | GΩ | Å3 | Å | Å | Å3 | Å | ||
| Hydrophilic amino acids | |||||||||
| Scale Lodishd | 189 | 4.86 | 0.440 | 11.0 | 980 | 5.20 | 15.5 | 354 | 9.3 |
| Scale #13d | 182 | 5.13 | 0.369 | 13.9 | 1,308 | 5.49 | 17.4 | 682 | 12.6 |
| Scale #18d | 185 | 4.71 | 0.690 | 6.8 | 1,503 | 8.05 | 15.4 | 877 | 11.8 |
| Scale #20d | 185 | 5.08 | 0.315 | 16.1 | 1,126 | 4.72 | 17.4 | 500 | 11.6 |
| Meane | 186 | 4.95 | 0.454 | 12.0 | 1,229 | 5.86 | 16.4 | 603 | 11.3 |
| SEM (n = 4) | 1 | 0.10 | 0.083 | 2.0 | 113 | 0.75 | 0.6 | 114 | 0.7 |
| Hydrophobic amino acids | |||||||||
| Scale Lodishd | 189 | 4.87 | 0.432 | 11.3 | 1,540 | 6.45 | 17.4 | 913 | 13.4 |
| Scale #13d | 197 | 4.74 | 0.316 | 15.0 | 1,481 | 5.41 | 18.7 | 854 | 14.2 |
| Scale #18d | 192 | 4.88 | 0.316 | 15.5 | 1,487 | 5.42 | 18.7 | 861 | 14.2 |
| Scale #20d | 181 | 5.21 | 0.289 | 18.0 | 1,485 | 5.18 | 19.1 | 859 | 14.5 |
| Meane | 190 | 4.92 | 0.338 | 14.9 | 1,498 | 5.62 | 18.5 | 872 | 14.1 |
| SEM (n = 4) | 3 | 0.10 | 0.032 | 1.4 | 14 | 0.29 | 0.4 | 13 | 0.2 |
| Parameterb | gT | R1 | R2 | R1/R2 | W | L | D | Wwtc | Dwtc |
| pS | GΩ | GΩ | Å3 | Å | Å | Å3 | Å | ||
| Hydrophilic amino acids | |||||||||
| Scale Lodishd | 189 | 4.86 | 0.440 | 11.0 | 980 | 5.20 | 15.5 | 354 | 9.3 |
| Scale #13d | 182 | 5.13 | 0.369 | 13.9 | 1,308 | 5.49 | 17.4 | 682 | 12.6 |
| Scale #18d | 185 | 4.71 | 0.690 | 6.8 | 1,503 | 8.05 | 15.4 | 877 | 11.8 |
| Scale #20d | 185 | 5.08 | 0.315 | 16.1 | 1,126 | 4.72 | 17.4 | 500 | 11.6 |
| Meane | 186 | 4.95 | 0.454 | 12.0 | 1,229 | 5.86 | 16.4 | 603 | 11.3 |
| SEM (n = 4) | 1 | 0.10 | 0.083 | 2.0 | 113 | 0.75 | 0.6 | 114 | 0.7 |
| Hydrophobic amino acids | |||||||||
| Scale Lodishd | 189 | 4.87 | 0.432 | 11.3 | 1,540 | 6.45 | 17.4 | 913 | 13.4 |
| Scale #13d | 197 | 4.74 | 0.316 | 15.0 | 1,481 | 5.41 | 18.7 | 854 | 14.2 |
| Scale #18d | 192 | 4.88 | 0.316 | 15.5 | 1,487 | 5.42 | 18.7 | 861 | 14.2 |
| Scale #20d | 181 | 5.21 | 0.289 | 18.0 | 1,485 | 5.18 | 19.1 | 859 | 14.5 |
| Meane | 190 | 4.92 | 0.338 | 14.9 | 1,498 | 5.62 | 18.5 | 872 | 14.1 |
| SEM (n = 4) | 3 | 0.10 | 0.032 | 1.4 | 14 | 0.29 | 0.4 | 13 | 0.2 |
Two-resistor model with R1 as a fixed resistor and R2 as a variable resistor (Fig. 1).
Formal definitions and equations for estimating the parameters by separately fitting data in Fig. 6 for amino acid substitutions classified as uncharged hydrophilic or hydrophobic are in the Appendix. gT is single-channel conductance, R1 is resistance of all parts of the conduction pathway, except the entrance to the inner cavity, and R2 is the resistance of the entrance to the inner cavity. W, L, and D are the calculated effective volume, length, and diameter of the entrance to the inner cavity. Values are for E321G/E324G channels unless indicated as for wt channels. All resistances and dimensions calculated assuming K+ is a point charge without volume or waters of hydration.
Wwt and Dwt are the calculated volume and diameter of the entrance to the inner cavity obtained for hypothetical neutral amino acids with the same volume as wt glutamate at positions 321/324. The calculated value of Lwt is the same as L.
The different hydrophobicity scales are from Lodish (2008) and Mant et al. (2009).
Mean values for the four different hydrophobicity scales above.