TABLE 2.
Proton dependence of time constants of wild type xASIC1.1, SQL mutant, and rat ASIC1a
Activation τa and desensitization τd time constants of xASIC1.1 wild type and the triple mutant xASIC1.1-SQL derived from outside-out patches activated by various concentrations of external protons. For comparison, rat ASIC1 rates are shown on the right columns. Owing to lower apparent proton affinity of rat ASIC1 compared to frog, currents evoked by pH 7.2 and 7.1 were too small to calculate the rates. Each value represent the mean of 10 to 20 activations recorded from two to four independent patches.
| pH | xASIC1.1 |
xASIC1.1-SQL |
rASIC1a |
|||
|---|---|---|---|---|---|---|
| τa | τd | τa | τd | τa | τd | |
| ms | Ms | ms | ||||
| 7.2 | 52 | 250 | 215 | 10,200 | ||
| 7.1 | 31 | 130 | 178 | 2500 | ||
| 6.8 | 12 | 65 | 60 | 800 | 180 | 2480 |
| 6.0 | 2 | 25 | 2 | 100 | 10 | 1700 |
| 5.5 | 1.5 | 18 | 1.5 | 50 | 6 | 670 |