title: Vacuolar H(+)-translocating pyrophosphatases: a new category of ion translocase.
abstract: The membrane surrounding the central vacuole of plant cells contains an H(+)-translocating ATPase (H(+)-ATPase) and an H(+)-translocating inorganic pyrophosphatase (H(+)-PPase). Both enzymes are abundant and ubiquitous in plants but the H(+)-PPase is unusual in its exclusive use of inorganic pyrophosphate (PPi) as an energy source. The lack of sequence identity between the vacuolar H(+)-PPase and any other characterized ion pump implies a different evolutionary origin for this translocase. The existence of the vacuolar H(+)-PPase, in conjunction with increasing recognition of PPi as a key metabolite in plant systems, necessitates reconsideration of ATP as the primary energy source for membrane transport in plant cells.
authors.affiliation: Department of Biology, University of Pennsylvania, Philadelphia 19104.
authors.forename: P A
authors.initials: PA
authors.lastname: Rea
authors.forename: Y
authors.initials: Y
authors.lastname: Kim
authors.forename: V
authors.initials: V
authors.lastname: Sarafian
authors.forename: R J
authors.initials: RJ
authors.lastname: Poole
authors.forename: J M
authors.initials: JM
authors.lastname: Davies
authors.forename: D
authors.initials: D
authors.lastname: Sanders
mesh_terms: D000595:Amino Acid Sequence; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D011756:Diphosphates / Q000378:metabolism*; D008969:Molecular Sequence Data; D010944:Plants / Q000378:metabolism; D017494:Proton Pumps; D006180:Proton-Translocating ATPases; D014617:Vacuoles / Q000378:metabolism*
chemical_list: D011756:Diphosphates; D017494:Proton Pumps; D006180:Proton-Translocating ATPases