Cells need to convert the energy derived from food to perform functions like muscle contractions. A “molecular machine” in the cell membrane plays a key role in this process. It works like a rotor and converts one component into another. Werner Kühlbrandt describes how the scientists used state-of-the-art electron microscopy to study the structure of this nanometer turbine down to the atomic level. The obtained data was then used to create a 3D model of the molecule. The surprising finding is the orientation of the rotor elements that goes against established knowledge of membrane molecule structure.