Effect of PMTS on ACh responses and ethanol modulation of α2β4 nAChRs, formed by wild-type or cysteine mutants of the α2 subunit
Initial current is the response evoked by EC50 ACh before the first coapplication with ethanol (see Materials and Methods and Fig. 4). Responses to EC50 ACh and its coapplication with 200 mM ethanol before and after 1-min application of 0.5 mM PMTS. The mutants α2(S256C)β4, α2(F260C)β4, α2(I264C)β4, and α2(E266C)β4 did not express. Values represent mean ± S.E.M. of four to eleven oocytes.
Receptor | Initial Current (nA) | EC50 ACh Responses (% Initial Response) | 200 mM Ethanol Modulation (% Change) | ||||
|---|---|---|---|---|---|---|---|
| Before PMTS | After PMTS | Before PMTS | After PMTS | ||||
| α2β4 wild-type | 2,700 ± 600 | 96 ± 1 | 88 ± 5 | 81 ± 9 | 77 ± 4 | ||
| α2(L257C)β4 | 4,600 ± 1,700 | 94 ± 2 | 79 ± 7 | 227 ± 25 | 284 ± 12a | ||
| α2(T258C)β4 | 1,720 ± 450 | 99 ± 4 | 89 ± 4a | 156 ± 10 | 154 ± 10 | ||
| α2(V259C)β4 | 3,800 ± 1,000 | 100 ± 1 | 154 ± 16a | 25 ± 6 | 19 ± 3 | ||
| α2(L261C)β4b | 3,000 ± 1,200 | 95 ± 2 | 84 ± 6 | 125 ± 14 | 119 ± 16 | ||
| α2(L262C)β4 | 2,430 ± 420 | 92 ± 3 | 26 ± 3a | 49 ± 5 | 237 ± 37a | ||
| α2(L263C)β4 | 750 ± 380 | 104 ± 3 | 237 ± 35a | 34 ± 8 | 6 ± 4a | ||
| α2(T265C)β4 | 2,360 ± 830 | 93 ± 2 | 98 ± 8 | 121 ± 5 | 134 ± 5 | ||
↵ a Significant effect of PMTS: p < 0.05 comparing values obtained before and after PMTS treatment.
↵ b Data from Borghese et al., 2002.