Detection of the voltage-sensing sensing elements in Cx26 (Maeda et al., 2009), transient receptor potential channel TRPV1 (Cao et al., 2013; Liao et al., 2013; Kasimova et al., 2018), and voltage-dependent anion channel VDAC1 (Ujwal et al., 2008). (A) Illustrated representation of the membrane proteins. The residues whose $ζ j$ value is larger than the detection threshold are shown. (B) $ζ j$ values estimated for Cx26, TRPV1, and VDAC1; the average and standard deviation are shown. The positively and negatively charged residues are shown as blue and red bars, respectively. The gray rectangles correspond to different regions of the proteins: NTH, the α-helical N terminus in Cx26 and VDAC1; TM1–TM4, transmembrane segments in Cx26; S1–S6, transmembrane segments in TRPV1; and β-barrel, the β-barrel in VDAC1.