TABLE 1.
Summary of results for holding current, currents evoked by ATP (30 μm), and effects of dithiothreitol, with distance between atoms
* p < 0.05; ** p < 0.005. For double mutants, distances between the Cβ atoms in the same subunit are also shown in italics.
| Receptor | Ihold (pA/pF) | IATP (pA/pF) | DTT (fold change) |
Cβ-Cβ (Å)a |
||
|---|---|---|---|---|---|---|
| Closed | Open | Closed | Open | |||
| Mean ± S.E. (n) | Mean ± S.E. (n) | Mean ± S.E. (n) | Mean ± S.E. (n) | |||
| Wild type | 1.7 ± 0.5 (11) | 571 ± 105 (12) | 0.83 ± 0.04 (11) | 0.99 ± 0.04 (9) | ||
| Turret | ||||||
| P89C | 5.6 ± 2.2 (4) | 34.8 ± 10.9 (4)** | 1.4 ± 0.2 (4) | 1.1 ± 0.2 (4) | 4.1 | 4.6 |
| P89S | 1.5 ± 0.3 (4) | 155 ± 67 (4) ** | 0.85 ± 0.05 (4) | 0.9 ± 0.09 (5) | ||
| P90C | 1.5 ± 0.3 (6) | 40.7 ± 3.8 (4)** | 8.5 ± 0.7 (4)** | 1.1 ± 0.07 (5) | 10.8 | 12.0 |
| P90S | 1.3 ± 0.3 (6) | 621 ± 117 (6) | 0.5 ± 0.07 (6)* | 1.0 ± 0.04 (6) | ||
| S97C | 2.6 ± 1.1 (4) | 315 ± 100 (4) | 0.77 ± 0.4 (4) | 1.0 ± 0.04 (4) | 16.7 | 16.0 |
| F291C | 2.1 ± 0.3 (4) | 26.5 ± 16.1 (4)** | 1.9 ± 0.4 (4) | 1.0 ± 0.04 (4) | 13.5 | 13.6 |
| P89C/S97C | 1.0 ± 0.09 (5) | 4.3 ± 1.0 (5)** | 12.6 ± 2.1 (5)** | 3.3 ± 0.7 (5)* | 10.7 | 10.0 |
| 8.1 | 7.7 | |||||
| P89C/F291C | 1.5 ± 0.6 (5) | 68.0 ± 32.5 (5)** | 0.2 ± 0.02 (5)** | 0.9 ± 0.06 (4) | 8.7 | 8.4 |
| 8.6 | 9.5 | |||||
| Lower body wall | ||||||
| T60C | 1.4 ± 0.4 (6) | 246 ± 78 (6)* | 2.2 ± 0.5 (6)* | 2.5 ± 0.7 (6)* | 7.6 | 14.1 |
| T60S | 1.9 ± 0.6 (4) | 620 ± 150 (4) | 0.88 ± 0.03 (4) | 1.0 ± 0.08 (5) | ||
| P62C | 2.5 ± 0.7 (4) | 313 ± 64 (4)* | 0.59 ± 0.11 (4) | 1.2 ± 0.2 (3) | 14.4 | 20.3 |
| S65C | 1.7 ± 0.2 (4) | 157 ± 108 (4) | 0.66 ± 0.18 (4)* | 1.0 ± 0.01 (4) | 18.8 | 20.9 |
| S190C | 2.0 ± 0.7 (4) | 259 ± 41 (4)* | 0.8 ± 0.05 (4) | 1.0 ± 0.02 (3) | 26.1 | 28.7 |
| H192C | 1.3 ± 0.1 (5) | 324 ± 79 (5) | 0.66 ± 0.05 (5)* | 0.9 ± 0.07 (3) | 24.1 | 29.2 |
| D315C | 5.2 ± 3.2 (4) | 197 ± 57 (4)** | 0.39 ± 0.09 (4)* | 1.0 ± 0.02 (4) | 16.5 | 16.8 |
| P62C/H192C | 2.3 ± 0.4 (8) | 29.5 ± 16.9 (8)** | 6.0 ± 1.6 (8)* | 2.4 ± 0.4 (5)* | 16.8 | 22.1 |
| 7.3 | 7.6 | |||||
| S65C/S190C | 1.5 ± 0.1 (8) | 34.4 ± 13.9 (8)** | 3.5 ± 0.3 (8)** | 2.9 ± 0.6 (7)* | 21.7 | 24.2 |
| 5.0 | 4.8 | |||||
| S65C/D315C | 3.6 ± 0.9 (7) | 122 ± 34 (7)** | 3.2 ± 0.45 (7)** | 2.8 ± 0.7 (4) | 5.2 | 6.8 |
| 15.1 | 15.2 | |||||
| Outer end of TM | ||||||
| V48C | 2.3 ± 0.9 (4) | 600 ± 120 (4) | 0.63 ± 0.05 (4)* | 0.94 ± 0.01 (4) | 18.6 | 21.8 |
| V51C | 2.4 ± 0.7 (4) | 365 ± 97 (4) | 0.81 ± 0.07 (4)* | 1.0 ± 0.08 (4) | 29.7 | 32.0 |
| S54C | 1.7 ± 1.0 (4) | 619 ± 201 (4) | 0.58 ± 0.2 (4)* | 0.95 ± 0.03 (4) | 14.9 | 21.6 |
| I328C | 4.2 ± 0.7 (5)* | 742 ± 130 (5) | 0.73 ± 0.05 (5)* | 1.11 ± 0.05 (5) | 15.6 | 27.9 |
| V48C/I328C | 16.1 ± 6.2 (5) | 15.0 ± 3.1 (5)** | 14.3 ± 3.5 (5)* | 1.6 ± 0.2 (4) | 5.4 | 14.6 |
| 14.5 | 14.9 | |||||
| V51C/I328C | 32.0 ± 8.6 (6)* | 64.3 ± 19.1 (5)** | 1.9 ± 0.3 (5)* | 0.96 ± 0.02 (3) | 10.3 | 15.2 |
| 20.0 | 20.0 | |||||
| S54C/I328C | 8.2 ± 2.2 (12)* | 14.1 ± 5.4 (6)** | 8.3 ± 2.4 (6)* | 5.6 ± 0.9 (11)* | 6.6 | 17.9 |
| 10.9 | 11.1 | |||||
a Mean of three measurements from each pair of subunits.