TABLE III.
Rate and Equilibrium Constants
| Construct | ko (s−1) | kc obs (s−1) | kc cor (s−1) | Keq | Agonist | Fold-change in Keq (mut/wt) | n |
|---|---|---|---|---|---|---|---|
| wta | 120 | 834 | 2583 | 0.046 | Cho | 1 | |
| wtb | 48000 | 1700 | 28.2 | ACh | 1 | ||
| A270T | 25332 (1645) | 2692 (611) | 3365 (764) | 7.53 (1.8) | ACh | 0.27 | 3 |
| A270W | 591 (38) | 319 (79) | 852 (212) | 0.69 (0.18) | Cho | 15.0 | 4 |
| A270F | 1717 (70) | 346 (36) | 924 (96) | 1.86 (0.15) | Cho | 40.4 | 3 |
| V271W | 58 (5.2) | 532 (36) | 1420 (97) | 0.04 (0.002) | Cho | 0.87 | 3 |
| V271I | 160 (13) | 988 (72) | 2638 (193) | 0.06 (0.007) | Cho | 1.3 | 3 |
| V271T | 36283 (3899) | 972 (71) | 1215 (89) | 29.9 (5.4) | ACh | 1.06 | 2 |
| V271F | 36 (2) | 161 (9) | 430 (25) | 0.08 (0.006) | Cho | 1.73 | 3 |
| P272G | 2737 (274) | 4821 (141) | 6026 (364) | 0.45 (0.03) | ACh | 0.02 | 4 |
| P272S | 29600 (1751) | 3252 (141) | 4065 (995) | 7.28 (2.2) | ACh | 0.26 | 4 |
| P272A | 2431 (42) | 83 (131) | 222 (46) | 10.9 (1.3) | Cho | 237 | 4 |
| L273V | 20967 (931) | 2649 (146) | 3311 (182) | 6.3 (1.0) | ACh | 0.22 | 3 |
| L273T | 32496 (1345) | 2486 (313) | 3108 (391) | 10.45 (2.0) | ACh | 0.37 | 3 |
| L273Y | 25825 (3001) | 1791 (586) | 2239 (732) | 11.53 (4.0) | ACh | 0.40 | 3 |
| I274V | 16057 (455) | 1770 (278) | 2213 (347) | 7.25 (1.2) | ACh | 0.25 | 3 |
| I274L | 26707 (1291) | 3494 (257) | 4368 (321) | 6.11(0.68) | ACh | 0.21 | 3 |
| I274F | 6210 (499) | 4608 (448) | 5760 (561) | 1.07 (0.18) | ACh | 0.04 | 3 |
| I274T | 439 (59) | 25085 (1093) | 31354 (1366) | 0.014 (0.002) | ACh | 0.0005 | 5 |
| G275L | 36716 (1028) | 3189 (293) | 3986 (366) | 9.21 (0.60) | ACh | 0.32 | 3 |
| G275S | 28365 (3174) | 3915 (710) | 4894 (888) | 5.79 (0.52) | ACh | 0.21 | 2 |
| G275P | 3380 (183) | 8510 (439) | 10638 (549) | 0.32 (0.03) | ACh | 0.01 | 3 |
| K276D | 35 (3) | 492 (43) | 1314 (116) | 0.03 (0.004) | Cho | 0.65 | 2 |
| K276A | 31689 (4998) | 2778 (219) | 3473 (273) | 9.12 (0.83) | ACh | 0.33 | 3 |
| K276W | 16628 (2353) | 1942 (35) | 2428 (43) | 6.84 (0.88) | ACh | 0.24 | 3 |
| K276I | 42316 (4227) | 5985 (418) | 7481 (522) | 5.65 (0.69) | ACh | 0.20 | 3 |
| V132A | 11949 (1755) | 2658 (192) | 3322 (240) | 3.59 (0.79) | ACh | 0.13 | 2 |
| V132I | 3093 (263) | 1579 (270) | 1973 (337) | 1.57 (0.14) | ACh | 0.06 | 3 |
| V132H | 1436 (232) | 1860 (201) | 2325 (252) | 0.62 (0.05) | ACh | 0.20 | 3 |
| V132F | 135 (38.5) | 10250 (795) | 12812 (994) | 0.01 (0.004) | ACh | 0.0004 | 2 |
| T133A | 16211 (1320) | 1940 (143) | 2425 (178) | 6.68 (0.59) | ACh | 0.24 | 3 |
| T133F | 7321 (776) | 1364 (117) | 1705 (146) | 4.3 (0.50) | ACh | 0.15 | 3 |
| T133V | 15793 (1971) | 2259 (1190) | 2824 (1488) | 5.59 (3.11) | ACh | 0.20 | 2 |
| T133H | 16751 | 1915 | 2394 | 6.99 | ACh | 0.25 | 1 |
| T133I | 17257 (1666) | 2127 (312) | 2659 (390) | 6.5 (1.61) | ACh | 0.23 | 2 |
| T133S | 21966 | 1658 | 2072 | 10.6 | ACh | 0.37 | 1 |
| H134Sc | 18474 | 2506 | 7.37 | ACh | 0.26 | ||
| H134R | 14730 (385) | 2496 (172) | 3120 (215) | 4.79 (0.4) | ACh | 0.17 | 4 |
| H134Q | 8884 (659) | 2599 (248) | 3249 (310) | 2.79 (0.3) | ACh | 0.1 | 3 |
| F135T | 8978 (1227) | 2833 (784) | 3541 (980) | 2.53 (0.32) | ACh | 0.09 | 3 |
| F135Y | 99 | 669 | 1786 | 0.05 | Cho | 1.08 | 1 |
| F135L | 7080 (794) | 3552 (331) | 4441 (413) | 1.59 (0.33) | ACh | 0.06 | 2 |
| F137L | 248 (44) | 875 (165) | 2336 (441) | 0.11 (0.04) | Cho | 2.4 | 3 |
| F137Y | 69 (5) | 783 (57) | 2091 (152) | 0.03 (0.004) | Cho | 0.66 | 3 |
ko, apparent opening rate constant; kc obs, apparent closing rate constant; kc cor, closing rate constant after correction for channel block; n, number of patches. Values are mean (±SEM). No rate constants are reported for P136G, A, S, and Y because no currents were detected for these constructs (5 patches each, 10 min/patch).
a
From Mitra et al. (2005).
c
From Chakrapani et al. (2004).