F1-ATPase is the catalytic, water-exposed sector of ATP synthase. In the isolated sector, ATP hydrolysis can drive rotation of a central shaft within a ring containing alternating alpha and beta subunits. In the complete membrane-coupled enzyme, rotation driven by the proton-motive force can instead support ATP synthesis. The direction depends on the coupled chemical and mechanical driving forces. [ref]
Molecular Biology of the Cell, 4th edition by Bruce Alberts and others. Chapter 14, ATP Synthase: reversible coupling of proton flow and ATP chemistry
A direct experiment attached a fluorescent actin filament to the central gamma subunit and immobilized the surrounding assembly. On adding ATP, the filament rotated, making nanometre-scale motor action visible through a much larger pointer. This demonstrated rotation during hydrolysis; demonstrating membrane-driven synthesis requires the additional membrane sector and an appropriate driving gradient. [ref]
Direct observation of the rotation of F1-ATPase by Hiroyuki Noji and others. 1997, abstract: fluorescent actin filament marker on gamma and ATP-driven rotation
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