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. Author manuscript; available in PMC: 2014 Oct 28.
Published in final edited form as: Nat Commun. 2014 Apr 28;5:3750. doi: 10.1038/ncomms4750

Figure 2. S4 residue accessibility shows two components of S4 movement in KCNQ1/KCNE1 channels.

Figure 2

(a) Current in response to a −20 mV voltage step before (trace 0) and during (traces 1-50) membrane-impermeable thiol reagent MTSET application on KCNQ1/KCNE1 A223C channels. External MTSET is applied at 0 mV for 20 s and then washed away for 12 s, before the cell is hyperpolarized to −120 mV for 12 s, as indicated by the voltage protocol (See Supplementary Figure 2 for details).

(b) MTSET modification rates at 0 mV and −80 mV using the current amplitudes measured at the arrow in a.

(c-d) Normalized voltage dependence of the modification rate for MTSET to residues 223C (black circle) and 224C (purple triangle) in (c) KCNQ1/KCNE1 and (d) KCNQ1 channels. Data are mean ± SEM for 5 to 8 cells in each group. Normalized F(V)(red) is shown for comparison.

(e-f) Cartoon models depicting voltage sensor movement in two steps in (e) KCNQ1/KCNE1 channels and in one step (f) KCNQ1 channel alone, respectively.