Notes on the mechanism of ATP synthesis

The most commonly quoted mechanism of the coupling between the electrochemi cal proton gradient and the formation of ATP from ADP and P-i assumes that all states of the FI portion of the ATP synthase have beta subunits in "tig ht," " loose," and "open" conformations. Models based on this assumption ar e inconsistent with some of the available experimental evidence. A mechanis m that includes an additional beta subunit conformation, "closed," observed in the rat liver structure overcomes these difficulties.