Gating profiles of reconstituted Δ1-21-mVDAC1-Y22C and cysteinless mVDAC1 variants

<p>. A) Top panel: representative traces of the Δ1-21-mVDAC1-Y22C gating activity at +10 and +40 mV. At +10 mV, a single channel reconstituted into the artificial membrane and conducted in the open state. At +40 mV the channel remained constitutively open. Bottom panel: Ohm-plot used for the determination of the conductance of the Δ1-21-mVDAC1-Y22C channel. The reconstituted channel responded linearly to application of both positive and negative potentials and exhibited a conductance of 4.00±0.04 nS (<i>n</i> = 20). This conductance was similar to that of the S0 state of the native protein (<i>P</i> = 0.80). B) Top panel: representative traces of the cysteinless variant at ±40 mV, following CuX₂Ph or DTT pre-treatment (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0047938#s2" target="_blank">materials and methods</a>). The gating behavior of the cysteinless variant was redox independent. Hence, the channel exhibited open (S0; blue) to closed (S1; red, S2; green) state transitions similar to those of the native channel. Bottom panel: Ohm-plot used for the determination of the conductance values of the corresponding states. Determined conductances were: S0; 3.78±0.09 nS (<i>n</i> = 28), S1; 2.55±0.12 nS (<i>n</i> = 24) and S2; 1.78±0.09 nS (<i>n</i> = 12). These conductances were similar to those of the native protein (S0; <i>P</i> = 0.42, S1; <i>P</i> = 0.24 and S2; <i>P</i> = 0.69). Bars represent standard errors of a minimum of 3 replicates per measurement. Values are given as mean ± SEM.