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. 2014 Apr 17;289(23):16452–16461. doi: 10.1074/jbc.M113.537134

FIGURE 3.

FIGURE 3.

KvAP lower affinity for DOTAP and titration of its effects by POPG. A, preferential affinity of KvAP for DPhPC over DOTAP within vesicles. KvAP channels were reconstituted in vesicles containing an increasing amount of DOTAP mixed with DPhPC: 0% (black), 50% (blue), 75% (green), and 100% (pink) DOTAP vesicles were fused to a DOTAP:DPhPC, 2:1, bilayer. No change in the midpoint of activation of the conductance-voltage relationship could be related to the increase of DOTAP concentration up to 75% in the pre-mixed vesicles. Data were fit with a single Boltzmann function (solid lines, Table 1) and V½ values are presented in the right panel. Number of assays are n = 2–7 and error bars are S.D. B, addition of negatively charged POPG in the bilayer titrates DOTAP effects. KvAP channels reconstituted in DOTAP vesicles were fused to a DOTAP bilayer containing 10 (green) or 20% (blue) POPG. For comparison, KvAP in DOTAP vesicles fused to DOTAP:DPhPC, 2:1, bilayer (pink) is shown. 10% of POPG in the bilayer is enough to shift the V½ value, but the VS value is not yet affected. With 20% of negative charges in the bilayer, the V½ and VS values are both restored to the POPE:POPG vesicles. The effect of DOTAP neutralization by POPG on the V½ is shown in the right panel. Values are shown in Table 1, n = 3–4, error bars are S.D.