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Updated: Aug 13, 2026

Assessment of Open Probability of the Mitochondrial Permeability Transition Pore in the Setting of Coenzyme Q Excess
Published on: June 1, 2022
H+ -PPases: a tightly membrane-bound family
M Baltscheffsky1, A Schultz, H Baltscheffsky
1Department of Biochemistry, Arrhenius Laboratories, Stockholm, Sweden. meg@biokemi.su.se
Abstract:
The earliest known H+-PPase (proton-pumping inorganic pyrophosphatase), the integrally membrane-bound H+-PPi synthase (proton-pumping inorganic pyrophosphate synthase) from Rhodospirillum rubrum, is still the only alternative to H+-ATP synthase in biological electron transport phosphorylation. Cloning of several higher plant vacuolar H+-PPase genes has led to the recognition that the corresponding proteins form a family of extremely similar proton-pumping enzymes. The bacterial H+-PPi synthase and two algal vacuolar H+-PPases are homologous with this family, as deduced from their cloned genes. The prokaryotic and algal homologues differ more than the H+-PPases from higher plants, facilitating recognition of functionally significant entities. Primary structures of H+-PPases are reviewed and compared with H+-ATPases and soluble PPases.
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