ATP synthase's second stalk comes into focus

Almost all the adenosine triphosphate (ATP, the predominant energy-transfer mediator in living organisms) used by cells is made by ATP synthases, which have two parts known as F1 and FO. These enzymes are found in bacterial plasma membranes, chloroplast thylakoid membranes and mitochondrial inner membranes; they function as rotary motors, coupling nucleotide binding in the F1 part to proton translocation by the transmembrane FO part1,2. Here we present cryoelectron microscopy images showing details of the connection between the F1 and FO parts of the enzyme.