| Species | Insertion | Mutation |
| Human | Leu 260 |
+L260 |
| Rat Equivalent | Leu 264 | +L264 |
| Mouse Equivalent |
The apparent affinity for ACh of this mutant was found to be 0.28 mM, compared to 2mM for the control. There was a small shift in the desensitization IC50.
| EC50 ACh (mM) | nH | IC50 ACh (mM) | nH | EC50 cytisine (mM) | nH | IMac ACh (nA) | |
| ha4(776ins3)b2 | .34 +/- 0.2 | 0.92 +/- 0.20 | 0.038 +/- 0.016 | 1.2 +/- 0.11 | 0.042 +/- 0.02 | 0.67 +/- 0.08 | 1624 +/- 569 |
| control | 3.4 +/- 2.7 |
0.70 +/- 0.05 | 0.11 +/- 0.02 | 1.4 +/- 0.15 | 2.12 +/- 1.7 | 0.79 +/- 0.14 | 1762 +/- 439 |
| Epibatidine nH |
Epibatidine Log intercept |
Acetylcholine nH |
Acetylcholine Log intercept |
Nictoine nH |
Nicotine Log intercept |
|
| ha4(776ins3)b2 | 1.12 +/- 0.13 | -5.63 +/- 0.4 | 1.15 +/- 0.14 | -3.55 +/- 0.36 | 1.12 +/- 0.22 | -3.62 +/- 0.64 |
| control | 1.21 +/- 0.17 | -5.13 +/- 0.32 | 1.2 +/- 0.27 | -3.16 +/- 0.47 | 1.24 +/- 0.27 | -3.10 +/- 0.62 |
In the control receptor cytisine evoked about 24.77% of ACh currents, but with this mutation it evoked about 78.2%. The EC50 for cytisine in the control was 2.12 mM, but in the mutant receptors, it was 0.042 mM.
Incubation with 320 mM Carbamazepine inhibited the ACh-evoked currents. The effect on the V287M mutant was greater than on the S252L mutant. a4S248F, a4L776ins3 and b2V287M are all more sensitive to CBZ than a4S252L.