Figure 5. . State-dependent accessibility of three S4 residues. (A–D) State-dependent accessibility of S261C. Currents before (A), during (B), and after (C) the intracellular application of 200 μM MTSEA. In (A) and (C), the voltage steps occur in –10 mV increments from −60 to −150 mV. In B, the voltage was held at 0 mV and then stepped to −140 mV for the test pulse, followed by a step to +50 mV for tail currents. The holding potential was 0 mV. The patch was excised into a bath containing 200 μM MTSEA. (D) Modification time course for intracellular MTSEA at 0 mV (•) and −140 mV (□). The current amplitudes are plotted versus their cumulative exposure to MTSEA. The bold line is an exponential fit. (E–G) State-independent accessibility of R247C. Currents before (E), during (F), and after (G) the extracellular application of 100 μM MTSET. In E and G, the voltage steps occur in −10-mV increments from 0 to −150 mV. In F, voltage was held at 0 mV and then stepped to −120 mV for the test pulse, followed by a step to 0 mV for tail currents. The tail currents during the application of 100 μM MTSET are shown in F. (H) Currents at the arrow in F as a function of cumulative exposure to MTSET. The modification time course for the extracellular application of MTSET at 0 mV (•) and at −100 mV (□). The bold lines are exponential fits to the data. (I–L) State-dependent accessibility of T249C. Currents before (I), during (J), and after (K) the application of 2 mM extracellular MTSET. In I and K, the voltage steps occur in −10-mV increments from 0 to −150 mV. In J, voltage was held at 0 mV and then stepped to −120 mV for the test pulse, followed by a step to +50 mV for tail currents. The holding potential was 0 mV. MTSET was applied for 10 s during each episode. (L) Currents at the arrow in J as a function of cumulative exposure to MTSET. Modification time course for the extracellular application of MTSET at 0 mV (•) and at −100 mV (□).
Image published in: Vemana S et al. (2004)
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