Figure 2. Single-channel currents of mutant human ɛ- and γ-AChRs.

Typical examples of single-channel openings recorded in the cell-attached configuration from GH4C1 cells transiently transfected with αV249Fβɛδ, αG153Sβɛδ, αV249Fβγδ or αG153Sβγδ AChR subunit cDNAs, as indicated. Under each trace is the corresponding distribution of burst durations, best-fitted by the sum of three exponential components. ACh concentration in the recording pipette was 100 nm. Channel conductance and time constants of the burst fitting components (weight) were: 45.4 pS, τ_b1 = 0.3 ms (18%), τ_b2 = 2.7 ms (19%), τ_b3 = 183 ms (62%) (αV249Fβɛδ; critical τ = 2 ms); 34.4 pS, τ_b1 = 0.6 ms (25%), τ_b2 = 1.8 ms (25%), τ_b3 = 64 ms (50%) (αV249Fβγδ; critical τ = 3 ms); 50.6 pS, τ_b1 = 0.2 ms (29%), τ_b2 = 2.9 ms (23%), τ_b3 = 16.8 ms (47%) (αG153Sβɛδ; critical τ = 1 ms); 26.3 pS, τ_b1 = 0.3 ms (30%), τ_b2 = 6.6 ms (23%), τ_b3 = 41.7 ms (47%) (αG153Sβγδ; critical τ = 1 ms). Traces filtered at 2 kHz for display purposes.