Fig. 5.
Dependence of Open Probability (Po) of the native and the phosphorylated (by JNK3) VDAC on applied membrane voltage (mV). The open probability of VDAC at a voltage V is defined as the fraction of time for which the channel was in open-state divided by the total time of recording it spent in partially closed sub-states. The open probability at a particular voltage is determined using pClamp 10.2 software by selecting the different current levels from the single-channel traces. At voltages ≤ ±20 mV native VDAC remains mainly in open-state, so its open-state probability was plotted against voltage (V) whereas at voltages >20 mV it also shows sub-state (s) so the open-probability of open-state (O) is calculated relative to the sub-states. In case of phosphorylated VDAC we did not observe characteristic VDAC open-state (∼4 nS) thus we have labeled its maximum current open-state as open P-state. We have compared the opening probability of native VDAC open-state (O) and the phosphorylated VDAC P-state (P). The scatter plots of the open probability versus voltage are made using Origin 5.0 software. Native VDAC plot is fitted with two Boltzmann functions one at positive and the other at the negative voltages, whereas of the phosphorylated VDAC is fitted with a single Boltzmann function. Values are Mean ± S.E. of three independent sets of best experiments.