title: Stoichiometry of energy coupling by proton-translocating ATPases: a history of variability.
abstract: One of the central energy-coupling reactions in living systems is the intraconversion of ATP with a transmembrane proton gradient, carried out by proton-translocating F- and V-type ATPases/synthases. These reversible enzymes can hydrolyze ATP and pump protons, or can use the energy of a transmembrane proton gradient to synthesize ATP from ADP and inorganic phosphate. The stoichiometry of these processes (H(+)/ATP, or coupling ratio) has been studied in many systems for many years, with no universally agreed upon solution. Recent discoveries concerning the structure of the ATPases, their assembly and the stoichiometry of their numerous subunits, particularly the proton-carrying proteolipid (subunit c) of the F(O) and V(0) sectors, have shed new light on this question and raise the possibility of variable coupling ratios modulated by variable proteolipid stoichiometries.
authors.affiliation: Wayne State University School of Medicine, Department of Biochemistry and Molecular Biology, Detroit, Michigan 48201, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: Tomashek
authors.forename: W S
authors.initials: WS
authors.lastname: Brusilow
mesh_terms: D049673:History, 20th Century; D009995:Osmosis; D021122:Protein Subunits; D006180:Proton-Translocating ATPases / Q000737:chemistry* / Q000235:genetics / Q000266:history / Q000378:metabolism*; D013816:Thermodynamics
chemical_list: D021122:Protein Subunits; D006180:Proton-Translocating ATPases