Fig. 3.

Kinetic analyses of α27′ double-mutants and hybrid. (A) Clusters of openings from AChRs having a Ser → Ile mutation at the α-subunit M2 27′ position (α269). Within a single patch there are three kinetically distinct cluster populations. (B) The cluster open probability distribution has three components that reflect the activity of AChRs having two (double-mutant), one (hybrid), and zero (WT) mutations. (C) REFER plot for α27′. The two α27′ positions make equal energetic contributions to and have progressed to the same extent at the transition state of the gating reaction (Φ = 0.65 ± 0.06).