α-Conotoxin MI dissociation constants (K D) for wild-type and mutant nicotinic receptors expressed from three and four subunit combinations
| Receptor subunit composition | KD, (αδ) (nM) | KDmt (αδ)/KDwt, (αδ) | KD, (αγ) (μM) | KDmt(αγ)/ KDwt, (αγ) |
|---|---|---|---|---|
| Wild-type | ||||
| α2βγδ | 0.54 | 1.00 | 18.4 | 1.00 |
| α2βδ2 | 1.34 | 1.00 | ||
| α2βγ2 | 11.7 | 1.00 | ||
| αY93F | ||||
| α2βγδ | 0.46 | 0.85 | 1.59 | 0.086 |
| α2βδ2 | 1.01 | 0.77 | ||
| α2βγ2 | 0.96 | 0.082 | ||
| αV188K | ||||
| α2βγδ | 0.98 | 1.81 | 120 | 6.52 |
| α2βδ2 | 2.74 | 2.09 | ||
| α2βγ2 | 44.7 | 3.82 |
K D values are averages from two separate transfections. In each transfection, a complete concentration profile is generated using duplicate sampling at each concentration (compare Figs. 3, 4, and 6). Transfection of α/β/γ/δ (2:1:1:1), α/β/γ (2:1:2), and α/β/δ (2:1:2) in the specified cDNA ratios yields the above stoichiometry of subunits (Sine and Claudio, 1991; Sine 1993).