Kinetic Analyses of AChR Mutants
| Construct . | Agonist . | k0 (s−1) . | kcobs (s−1) . | kccor (s−1) . | Keq (ko/kccor) . | Normalized Keq (mut/wt) . | n . |
|---|---|---|---|---|---|---|---|
| wt | Choa | 120 | – | 2583 | 0.046 | 1 | – |
| wt | AChb | 48000 | – | 1700 | 28.2 | 1 | – |
| wt | CCh | 7721 | – | 1138 | 6.8 | 1 | – |
| Y127F | Cho | 2853 (221) | 390 (20.3) | 1041.3 (107) | 2.7 (0.28) | 58.7 | 4 |
| Y127W | Cho | 1518 (170) | 353 (122) | 943 (234) | 1.6 (0.4) | 34.8 | 2 |
| Y127H | Cho | 520 (68) | 577 (86) | 1541 (295) | 0.33 (0.01) | 7.2 | 4 |
| Y127P | ACh | 3008 | 5498 | 6872.5 | 0.43 | 0.015 | 1 |
| Y127L | ACh | 2351 (217) | 6277 (536) | 7846 (670) | 0.29 (0.05) | 0.01 | 4 |
| Y127G | ACh | 2009 (95) | 5676 (247) | 7095 (309) | 0.28 (0.03) | 0.01 | 2 |
| Y127E | ACh | 1166 (153) | 3411 (306) | 4264 (382) | 0.27 (0.05) | 0.01 | 4 |
| Y127A | ACh | 1726 (97) | 5447 (332) | 6809 (416) | 0.25 (0.03) | 0.009 | 3 |
| Y127Q | ACh | 1570 (70) | 5126 (104) | 6408 (130) | 0.24 (0.01) | 0.009 | 5 |
| Y127N | ACh | 1574 (36) | 5506 (353) | 6883 (441) | 0.22 (0.01) | 0.008 | 3 |
| Y127C | ACh | 862 (119) | 4674 (248) | 5843 (310) | 0.14 (0.03) | 0.005 | 4 |
| Y127S | ACh | 1076 (94) | 5953 (522) | 7442 (653) | 0.14 (0.03) | 0.005 | 2 |
| Y127M | ACh | 555 (101) | 4952 (340) | 6190 (425) | 0.089 (0.02) | 0.003 | 4 |
| Y127T | ACh | 550 (7) | 7619 (569) | 9524 (711) | 0.057 (0.004) | 0.002 | 4 |
| Y127R | ACh | 336 (25) | 5273 (363) | 6591 (454) | 0.051 (0.003) | 0.0018 | 3 |
| Y127I | ACh | 208 (44) | 5763 (533) | 7204 (667) | 0.028 (0.006) | 0.001 | 2 |
| Y127K | ACh | 238 (57) | 8556 (585) | 10690 (732) | 0.022 (0.005) | 0.0008 | 3 |
| Y127V | ACh | 112 (4) | 8230 (1388) | 10288 (1374) | 0.010 (0.001) | 0.0004 | 3 |
| Y127D | ACh | 29 (12) | 3966 (435) | 4958 (543) | 0.0057 (0.002) | 0.0002 | 3 |
| Y127P | CCh | 2956 | 2386 | 5843 | 0.51 | 0.075 | 1 |
| Y127A | CCh | 603 (38) | 2600 (91) | 6162 (517) | 0.098 (0.01) | 0.014 | 3 |
| Y127E | CCh | 175 (21) | 1082 (274) | 2617 (651) | 0.07 (0.01) | 0.01 | 2 |
| I49C | ACh | 39200 (1593) | 1828 (116) | 2285 (145) | 17.2 (0.42) | 0.6 | 3 |
| I49Y | ACh | 39280 (4000) | 3574 (316) | 4468 (395) | 8.8 (0.45) | 0.3 | 3 |
| Construct . | Agonist . | k0 (s−1) . | kcobs (s−1) . | kccor (s−1) . | Keq (ko/kccor) . | Normalized Keq (mut/wt) . | n . |
|---|---|---|---|---|---|---|---|
| wt | Choa | 120 | – | 2583 | 0.046 | 1 | – |
| wt | AChb | 48000 | – | 1700 | 28.2 | 1 | – |
| wt | CCh | 7721 | – | 1138 | 6.8 | 1 | – |
| Y127F | Cho | 2853 (221) | 390 (20.3) | 1041.3 (107) | 2.7 (0.28) | 58.7 | 4 |
| Y127W | Cho | 1518 (170) | 353 (122) | 943 (234) | 1.6 (0.4) | 34.8 | 2 |
| Y127H | Cho | 520 (68) | 577 (86) | 1541 (295) | 0.33 (0.01) | 7.2 | 4 |
| Y127P | ACh | 3008 | 5498 | 6872.5 | 0.43 | 0.015 | 1 |
| Y127L | ACh | 2351 (217) | 6277 (536) | 7846 (670) | 0.29 (0.05) | 0.01 | 4 |
| Y127G | ACh | 2009 (95) | 5676 (247) | 7095 (309) | 0.28 (0.03) | 0.01 | 2 |
| Y127E | ACh | 1166 (153) | 3411 (306) | 4264 (382) | 0.27 (0.05) | 0.01 | 4 |
| Y127A | ACh | 1726 (97) | 5447 (332) | 6809 (416) | 0.25 (0.03) | 0.009 | 3 |
| Y127Q | ACh | 1570 (70) | 5126 (104) | 6408 (130) | 0.24 (0.01) | 0.009 | 5 |
| Y127N | ACh | 1574 (36) | 5506 (353) | 6883 (441) | 0.22 (0.01) | 0.008 | 3 |
| Y127C | ACh | 862 (119) | 4674 (248) | 5843 (310) | 0.14 (0.03) | 0.005 | 4 |
| Y127S | ACh | 1076 (94) | 5953 (522) | 7442 (653) | 0.14 (0.03) | 0.005 | 2 |
| Y127M | ACh | 555 (101) | 4952 (340) | 6190 (425) | 0.089 (0.02) | 0.003 | 4 |
| Y127T | ACh | 550 (7) | 7619 (569) | 9524 (711) | 0.057 (0.004) | 0.002 | 4 |
| Y127R | ACh | 336 (25) | 5273 (363) | 6591 (454) | 0.051 (0.003) | 0.0018 | 3 |
| Y127I | ACh | 208 (44) | 5763 (533) | 7204 (667) | 0.028 (0.006) | 0.001 | 2 |
| Y127K | ACh | 238 (57) | 8556 (585) | 10690 (732) | 0.022 (0.005) | 0.0008 | 3 |
| Y127V | ACh | 112 (4) | 8230 (1388) | 10288 (1374) | 0.010 (0.001) | 0.0004 | 3 |
| Y127D | ACh | 29 (12) | 3966 (435) | 4958 (543) | 0.0057 (0.002) | 0.0002 | 3 |
| Y127P | CCh | 2956 | 2386 | 5843 | 0.51 | 0.075 | 1 |
| Y127A | CCh | 603 (38) | 2600 (91) | 6162 (517) | 0.098 (0.01) | 0.014 | 3 |
| Y127E | CCh | 175 (21) | 1082 (274) | 2617 (651) | 0.07 (0.01) | 0.01 | 2 |
| I49C | ACh | 39200 (1593) | 1828 (116) | 2285 (145) | 17.2 (0.42) | 0.6 | 3 |
| I49Y | ACh | 39280 (4000) | 3574 (316) | 4468 (395) | 8.8 (0.45) | 0.3 | 3 |
All values pertain to fully liganded AChRs. ko, apparent opening rate constant; kcobs, observed closing rate constant; kccor, closing rate constant corrected for channel block; Keq, diliganded gating equilibrium constant; normalized Keq (divided by the wt value for the salient agonist); n, number of patches. The mutant/wt ratio is with regard to the diliganded gating equilibrium constant.
From Mitra et al. (2005).
From Chakrapani and Auerbach (2005).