Figure 7. Pore Blockers and Closed Channels Impede Access to Cysteine Mutations.
(A) Representative IHC sensory transduction currents for WT, G411C, M412C, and D569C in response to dual application of 2 mM dihydrostreptomycin (DHS) and MTSET as indicated above. MTSET was applied at 2 mM for G411C, 10 mM for M412C, and 0.2 mM for D569C, selected as the minimal concentration required to achieve the maximal response during the 8-s application. The scale bars represent 2 s (horizontal) and 100 pA (vertical).
(B) IHC responses for dual application of 2 mM amiloride and MTSET. Scale bars indicate 2 s (horizontal) and 100 pA (vertical).
(C) Mean (±SEM) current ratios for WT, G411C, M412C, and D569C in response to MTSET alone, DHS + MTSET, or amiloride + MTSET. Number of cells, from 2–5 mice/condition, is shown at the bottom of each bar.
(D) Mean sensory transduction current traces (black) superimposed on 10–15 normalized individual traces (gray) recorded from utricle type II hair cells expressing M412C. Deflection protocol is shown below. Between each step, the bundle was deflected 1.7 μm (top row) or −0.5 μm (bottom row) for 6 s to open or close channels, respectively. 2 mM MTSET was applied between the 2nd and 3rd steps as indicated. The scale bar represents 25 ms.
(E) Mean sensory transduction traces (black) superimposed on 6–8 normalized individual traces (gray) recorded from utricle type II hair cells expressing D569C.The same stimulation protocol was used to evoke the responses shown in (D) and (E) except the bundle was deflected for 2 s and the MTSET concentration was 0.5 mM.
(F) Mean (±SEM) normalized M412C and D569C currents for each step (1–3) shown in (D) and (E) for bundles held in the open and closed positions. Number of cells, from 2–5 mice/condition, is shown above the bars.