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. 2020 Jan 3;10(1):78. doi: 10.3390/biom10010078

Figure 1.

Figure 1

Channel activity of the SecYEG-RNC (ribosome-nascent chain) complex. (A) The planar bilayer did not show channel activity when only SecYEG-containing vesicles were added to the cis compartment (φ = −85 mV). (B) However, the subsequent addition of RNCs resulted in channel activity (φ = −85 mV). (C) Augmenting the membrane potential to φ = −140 mV resulted in channel closure. The negative potential induces the current to flow in the negative direction of the y-axis. Thus, the apparent movement upstairs indicates stepwise channel closure. The number of open channels is indicated on the right side. It decreases from five open channels at the moment of switching the potential to −140 mV, to zero open channels after little more than one second has elapsed. (D) Channel lifetime histogram for φ = −140 mV. From the single-exponential fit (blue) we extracted a channel lifetime of about 0.5 s. The colored schemes show SecYEG (light gray), the ribosome (dark grey), the nascent chain (blue), SecYEG’s helix 2b (red), and SecYEG’s plug domain (green).