Table 2. Maximal fitted response and potency of ACh and NS9283 from concatenated α4β2 nAChRs.
| Construct | Subunit | ACh | NS9283 | Both | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Emax | pEC50_1 | pEC50_2 | Frac | n | E31.6 µM | Emax | pEC50 | n | AChmax current | ||||
| % | % | % | nA | ||||||||||
| α4 (10:1) | β2 | 102 ± 1 | 5.7 ± 0.3 | 3.9 ± 0.04 | 0.11 ± 0.03 | 14 | 760 ± 70 | 860 ± 60 | 5.3 ± 0.1 | 13 | 8,100 ± 900 (27) | ||
| α4VFL (10:1) | β2 | 104 ± 2 | 5.0 ± 0.1 | 3.9 ± 0.3 | 0.71 ± 0.12 | 9 | −9.9 ± 1.8 | No pos. pot. | N/A | 16 | 1,700 ± 300 (25) | ||
| Tetrameric | |||||||||||||
| β-6-α-9-β-6-α | 109 ± 5 | 5.7 ± 0.2 | 3.8 ± 0.2 | 0.45 ± 0.07 | 6 | 170 ± 20 | 220 ± 30 | 5.0 ± 0.2 | 6 | 49 ± 9 (12) | |||
| β-6-α-9-β-6-α | α4 | 100 ± 1 | 5.9 ± 0.8 | 3.8 ± 0.04 | 0.035 ± 0.020 | 8 | 1,100 ± 100 | 1,300 ± 100 | 5.2 ± 0.1 | 6 | 1,500 ± 300 (14) | ||
| β-6-α-9-β-6-α | α4VFL | 109 ± 4 | 5.0 ± 0.2 | 3.6 ± 0.2 | 0.41 ± 0.09 | 9 | 130 ± 10 | 170 ± 20 | 5.0 ± 0.2 | 5 | 720 ± 130 (14) | ||
| β-6-α-9-β-6-α (1:5) | α4VFL | 102 ± 2 | 5.5 ± 0.3 | 4.2 ± 0.2 | 0.32 ± 0.13 | 13 | 100 ± 10 | 130 ± 20 | 5.1 ± 0.2 | 6 | 850 ± 170 (19) | ||
| β-6-α-9-β-6-α (1:25) | α4VFL | 106 ± 2 | 5.4 ± 0.1 | 4.0 ± 0.2 | 0.40 ± 0.12 | 9 | 130 ± 10 | 140 ± 10 | 5.4 ± 0.1 | 8 | 310 ± 40 (15) | ||
| Pentameric | |||||||||||||
| β-21a-α-β-α-α | 101 ± 1 | 5.9 ± 0.3 | 3.7 ± 0.02 | 0.060 ± 0.011 | 12 | 930 ± 30 | 1,100 ± 40 | 5.1 ± 0.1 | 14 | 2,300 ± 400 (15) | |||
| β-21a-α-β-α-αVFL | 105 ± 1 | 5.2 ± 0.1 | 4.0 ± 0.2 | 0.59 ± 0.07 | 14 | 41 ± 4 | 48 ± 5 | 5.3 ± 0.2 | 19 | 2,400 ± 400 (22) | |||
| β-21a-α-α-β-α | 100 ± 2 | 6.1 ± 0.6 | 4.0 ± 0.05 | 0.060 ± 0.025 | 14 | 780 ± 90 | 910 ± 70 | 5.3 ± 0.1 | 9 | 5,300 ± 700 (23) | |||
| β-21a-α-αVFL-β-α | 102 ± 2 | 5.3 ± 0.2 | 4.3 ± 0.2 | 0.46 ± 0.18 | 19 | 55 ± 6 | 75 ± 9 | 5.0 ± 0.2 | 23 | 2,000 ± 200 (39) | |||
| β-21a-αVFL-α-β-α | 104 ± 1 | 5.2 ± 0.1 | 4.1 ± 0.1 | 0.44 ± 0.1 | 12 | 85 ± 10 | 102 ± 10 | 5.2 ± 0.1 | 12 | 600 ± 60 (12) | |||
| β-3a-α-β-α-α | 102 ± 1 | 6.0 ± 0.3 | 4.0 ± 0.04 | 0.11 ± 0.02 | 9 | 640 ± 90 | 800 ± 90 | 5.1 ± 0.2 | 5 | 700 ± 120 (14) | |||
| β-3a-α-β-α-αVFL | 104 ± 1 | 5.4 ± 0.1 | 4.3 ± 0.1 | 0.53 ± 0.08 | 14 | 11 ± 2 | 13 ± 1a | 5.8 ± 0.2 | 15 | 1,400 ± 400 (29) | |||
| β-3a-αVFL-β-α-α | 105 ± 1 | 5.6 ± 0.1 | 4.1 ± 0.1 | 0.39 ± 0.05 | 15 | 200 ± 20 | 240 ± 20 | 5.2 ± 0.1 | 9 | 440 ± 80 (24) | |||
| β-3a-αVFL-α-β-α | 105 ± 4 | 5.1 ± 0.3 | 3.6 ± 0.2 | 0.28 ± 0.10 | 9 | 270 ± 10 | 340 ± 20 | 5.1 ± 0.1 | 12 | 730 ± 120 (17) | |||
Data for ACh and NS9283 obtained from tetrameric or pentameric concatenated constructs are handled and presented as described in Table 1. Longer incubation times of 3–7 d were generally utilized to increase expression levels. Data for α4 and β2 or α4VFL and β2 are from Table 1 for reference purposes. No pos. pot., no positive potentiation.
a
No NS9283 efficacy observed in ∼50% of oocytes, resulting in poor fitting, as evidenced by the apparent increase in potency.