TI loop mutations differently affect the voltage sensor dynamics.

<p>On-sensing currents of Ci-VSP were recorded from a holding potential of −60 mV in response to variable test pulses between −40 to+160 mV at maximum (increment: 20 mV, duration: 500 ms). Off-sensing currents were monitored by stepping back to −50 mV after the test potential phase (off-pulse duration: 500 ms). <i>(</i><b><i>A–D</i></b><i>)</i> Representative full current traces are shown for the WT and the denoted mutants. From these signals, selected off-currents are zoomed out (40 mV increments). As described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0070272#s4" target="_blank">Materials and Methods</a>, Q<sub>off,all</sub>-V-distributions were calculated by integrating the off-sensing currents. These distributions are plotted against the potential of the preceding test pulse phase. From the whole amount of translocated sensing charges (Q<sub>off,all</sub>), the fast (Q<sub>off,fast</sub>) and the slow (Q<sub>off,slow</sub>) component was determined as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0070272#s4" target="_blank">Materials and Methods</a>. All calculated Q<sub>off</sub>-values were normalized to the Q<sub>off,all</sub>-value corresponding to the test potential of+120 mV. Q<sub>off,all</sub>-V-distributions were approximated with a Boltzmann-type function (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0070272#s4" target="_blank">Materials and Methods</a>). Parameters of voltage-dependence (V<sub>0.5</sub>, z<sub>q</sub>) are given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0070272#pone.0070272.s008" target="_blank">Table S3</a>.</p>