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Comment
. 2015 Dec;146(6):435-9.
doi: 10.1085/jgp.201511534.

Modal gating of endplate acetylcholine receptors: A proposed mechanism

Yanyan Geng  1 , Karl L Magleby  2
Affiliations
Comment

Modal gating of endplate acetylcholine receptors: A proposed mechanism

Yanyan Geng et al. J Gen Physiol. 2015 Dec.
No abstract available

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Figures

Figure 1.
Figure 1.
Examples of transient modal gating (mode shifting) in BK channels taken from the study of McManus and Magleby (1988). (A) A continuous single-channel current record (divided into three traces) recorded from a single BK channel. The inside-out patch-clamp configuration (Hamill et al., 1981) was used to record the data. The patch of membrane was pulled from a skeletal muscle cell in a primary culture of rat skeletal muscle. Channel opening is upward. The downward and upward arrows indicate switching from normal mode gating into brief open mode gating and then back, respectively. (B) Stability plot of the moving average of open-interval durations taken 50 at a time. Shifting from normal mode gating, with a mean open interval duration of 2.8 ms, to brief open-mode gating, with a mean open interval duration of 0.5 ms, and then back to normal mode gating is readily apparent. (C and D) Current record (C) and stability plot (D) for mode shifting into and out of a buzz mode with a mean open interval of 0.05 ms. Symmetrical 144 mM KCl; 30 mV; 7.5 µM Ca2+i; pH 7.2.
Figure 2.
Figure 2.
Stable modal gating in adult endplate AChRs. (A) Stable normal-mode gating. (Left) Continuous single-channel recording displayed as seven traces obtained with on-cell patch-clamp recording from HEK cells with expressed WT mouse AChRs. Opening is downward. The clusters of activity arise from AChRs coming out of desensitization (D) to gate (C-O), and then returning to desensitization. (Middle) Histogram of the number of clusters versus their mean Po. Only a single normal mode of activity is seen with a Po of 0.7. (Right) Dwell-time distributions of shut- and open-interval durations are each described by a single exponential, indicating gating in two states (C-O). (B) Four stable modes of gating after the mutation P197A in the α subunits. (Left) Single-channel current record during continuous recording displayed as seven traces. (Middle) Gating in four different stable modes with mean durations of 0.01, 0.20, 0.67, and 0.96. (Right) The dwell-time distributions of the entire current record are described by multiple exponentials, indicating different kinetics for the different modes. See Fig. 2 of Vij et al. (2015) for further details.
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References

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