Gating Rate Constants for Mutations in Loop A of Non-α-subunits Activated by Choline
Construct . | β2 . | α2* . |
|---|---|---|
| s−1 | s−1 | |
| wt | 100 | 1,100 |
| β-subunit | ||
| D97A | 72 | 1,320 |
| D97V | 85 | 762 |
| G98A | 49 | 861 |
| G98V | 80 | 471 |
| δ-subunit | ||
| N98V | 62 | 437 |
| N98A | 36 | 1,335 |
| D99A | 146 | 630 |
| D99V | 117 | 561 |
| ε-subunit | ||
| D97A | 64 | 645 |
| D97V | 103 | 933 |
Construct . | β2 . | α2* . |
|---|---|---|
| s−1 | s−1 | |
| wt | 100 | 1,100 |
| β-subunit | ||
| D97A | 72 | 1,320 |
| D97V | 85 | 762 |
| G98A | 49 | 861 |
| G98V | 80 | 471 |
| δ-subunit | ||
| N98V | 62 | 437 |
| N98A | 36 | 1,335 |
| D99A | 146 | 630 |
| D99V | 117 | 561 |
| ε-subunit | ||
| D97A | 64 | 645 |
| D97V | 103 | 933 |
Channel opening (β2) and closing (α2*) rate constants were measured at a saturating concentration of choline (20 mM). Because channel block prolongs the apparent open-interval lifetimes, α2* values are ∼2-fold smaller than the α2 values measured at low choline concentrations (see Table II).