Figure 3.

Overview of our proposed torque-generating mechanism. Cation binding induces a strain in the stator, which causes the loops to bend. This results in the first half of the power stroke (here, by Loop 1), and sets up the second loop (here, Loop 3) to perform its half of the power stroke. Subsequently, the cations are released into the cytoplasm. This occurs because our proposed motion also has a vertical component—the loops lower themselves out of the membrane. This release then reverses the strain and causes the loops to restraighten. This results in the second half of the power stroke. We note that this image depicts a two-dimensional projection of a three-dimensional motion: stator motion is not constrained to the plane of the page. To see this figure in color, go online.