Table 4.
Fitting linear versus cyclic models to single-channel currents from AChRs activated by low [ACh]
| Model | kon | koff | f0 | b0 | jon | joff | f1 | b1 | LL | nfp |
 | 398 ± 39 | 5,457 ± 513 | 297 ± 3 | 8,883 ± 64 | – | – | 299 ± 7 | 234 ± 3 | 365,875 | 6 |
 | – | – | 303 ± 2 | 8,435 ± 63 | 470 ± 8 | 371 ± 6 | 2,911 ± 350 | 29 ± 2 | 366,151 | 6 |
 | 10 ± 1 | 5,086 ± 790 | 290 ± 12 | 8,404 ± 348 | 395 ± 19 | 272 ± 12 | 2,032 ± 182 | 78 ± 4 | 366,306 | 7 |
| Model | kon | koff | f0 | b0 | jon | joff | f1 | b1 | LL | nfp |
| | 398 ± 39 | 5,457 ± 513 | 297 ± 3 | 8,883 ± 64 | – | – | 299 ± 7 | 234 ± 3 | 365,875 | 6 |
| | – | – | 303 ± 2 | 8,435 ± 63 | 470 ± 8 | 371 ± 6 | 2,911 ± 350 | 29 ± 2 | 366,151 | 6 |
| | 10 ± 1 | 5,086 ± 790 | 290 ± 12 | 8,404 ± 348 | 395 ± 19 | 272 ± 12 | 2,032 ± 182 | 78 ± 4 | 366,306 | 7 |
In the full cycle (Fig. 5 B, inset), the agonist (A) could bind to both the C (low affinity) and O (high affinity) conformations. Rate constants (mean ± SD) were from the global cross-concentration fit (n = 64,790 intervals; s−1 or µM−1s−1). kon, low affinity association rate constant; koff, low affinity dissociation rate constant; jon, high affinity association rate constant; joff, high affinity dissociation rate constant; LL, loglikelihood; nfp, number of free parameters. fn and bn are the opening and closing rate constants with n-bound agonists. From the gating rate constants of the cyclic model, E1 = 26 and E0 = 0.035 (E1/E0 = 742).