Table 1.
Characterization of nAChR/5-HT3R subunit chimaeras
| Loop chimaera | [125I]αBTX binding (fmol mg−1) (n=4–7) | [3H]MLA binding (fmol mg−1) (n=5) | Functional expression | Conductance (pS) (n=5–9) | Time constant for desensitization (ms) (n=6–21) | Targeting (MDCK cells) |
|---|---|---|---|---|---|---|
| α1 loop (α7/5-HT3Aα1-loop) | 1857±346a | 1424±111c | No | ND | ND | Non-polarized |
| α2 loop (α7/5-HT3Aα2-loop) | 132±34b | 353±39d | No | ND | ND | ND |
| α3 loop (α7/5-HT3Aα3-loop) | 502±158 | 388±75d | Yes | 29.4±2.8e | 278±23g | ND |
| α4 loop (α7/5-HT3Aα4-loop) | 1457±259a | 1635±197c | No | ND | ND | Apical |
| α5 loop (α7/5-HT3Aα5-loop) | 139±48b | 1008±148c | No | ND | ND | ND |
| α6 loop (α7/5-HT3Aα6-loop) | 718±193 | 1037±50c | No | ND | ND | ND |
| α7 loop (α7/5-HT3Aα7-loop) | 1391±307a | 1187±89c | Yes | 36.1±3.2e | 1334±141h | Apical |
| α8 loop (α7/5-HT3Aα8-loop) | 1442±429a | 1139±189c | Yes | 24.9±0.8e | 967±184h | Apical |
| α9 loop (α7/5-HT3Aα9-loop) | 13±5b | 272±41d | No | ND | ND | ND |
| α10 loop (α7/5-HT3Aα10-loop) | 179±69b | 592±60 | Yes | 10.5±1.7f | 217±16g | ND |
| β1 loop (α7/5-HT3Aβ1-loop) | 129±48b | 381±50d | No | ND | ND | ND |
| β2 loop (α7/5-HT3Aβ2-loop) | 41±16b | 775±24 | No | ND | ND | ND |
| β3 loop (α7/5-HT3Aβ3-loop) | 40±12b | 269±18d | No | ND | ND | ND |
| β4 loop (α7/5-HT3Aβ4-loop) | 5±2b | 88±10d | No | ND | ND | ND |
Abbreviations: αBTX, α-bungarotoxin; MDCK, Madin–Darby canine kidney; MLA, methyllycaconitine; ND, not determined.
Data shown are means±s.e.mean.
Statistical significance: a vs b P<0.05, c vs d P<0.05, e vs f P<0.001, g vs h P<0.001.