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. 2022 Sep 27;119(40):e2208034119. doi: 10.1073/pnas.2208034119

Fig. 4.

Fig. 4.

Mechanics of Piezo activation. (A) Three-dimensional plots of the Piezo dome and its (partial) membrane footprint in the limit of an asymptotically planar membrane. We assume here that the closed state of Piezo approximately corresponds to the intrinsic Piezo dome radius of curvature RP=Rc42 nm (Left) and that the open state of Piezo approximately corresponds to a flat Piezo dome shape with radius of curvature RP=Ro (Right). We calculated the shape of the membrane footprint by minimizing the shape energy of the Piezo–membrane system, Gsys(RP) in Eq. 5, at fixed RP with AP=450 nm2. In A, Left, we used a nominal lateral membrane tension γ=0.01 kBTnm2. The membrane areas occupied by the Piezo dome as well as by the membrane footprint are identical in A, Left and Right. (BD) Piezo gating curves, Po(γ) in Eq. 6, for the elastic properties of the Piezo dome estimated in Fig. 3, R042 nm and KP18 kBT, with the Piezo dome area AP=450 nm2 (black curves) and with (B) a modified intrinsic Piezo dome radius of curvature 12R0 (blue solid curve) or 2R0 (blue dashed curve), (C) a modified Piezo dome bending rigidity 32KP (thick red curve) or 2KP (thin red curve), and (D) a modified Piezo dome area 23AP (thick green curve) or 12AP (thin green curve). For the predicted Piezo gating curve with R042 nm, KP18 kBT, and AP=450 nm2, Eq. 6 yields Po=12 at the gating tension γ1/20.33 kBTnm2 (black curves). In B, γ1/20.34 kBTnm2 for 12R0 and γ1/20.32kBTnm2 for 2R0. In C, γ1/20.56 kBTnm2 for 32KP and γ1/20.83 kBTnm2 for 2KP. In D, γ1/20.49 kBTnm2 for 23AP and γ1/20.65 kBTnm2 for 12AP.