title: H+ -PPases: a tightly membrane-bound family.
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.
authors.affiliation: Department of Biochemistry, Arrhenius Laboratories, Stockholm, Sweden. meg@biokemi.su.se
authors.forename: M
authors.initials: M
authors.lastname: Baltscheffsky
authors.forename: A
authors.initials: A
authors.lastname: Schultz
authors.forename: H
authors.initials: H
authors.lastname: Baltscheffsky
mesh_terms: D000595:Amino Acid Sequence; D002462:Cell Membrane / Q000201:enzymology*; D019143:Evolution, Molecular; D043564:Inorganic Pyrophosphatase; D008969:Molecular Sequence Data; D010944:Plants / Q000201:enzymology*; D011387:Prokaryotic Cells / Q000502:physiology; D011755:Pyrophosphatases / Q000378:metabolism*; D012247:Rhodospirillum rubrum / Q000201:enzymology; D017386:Sequence Homology, Amino Acid; D014617:Vacuoles / Q000201:enzymology
chemical_list: D011755:Pyrophosphatases; D043564:Inorganic Pyrophosphatase