title: Vacuolar proton-pumping pyrophosphatase in Beta vulgaris shows vectorial activation by potassium.
abstract: Previous work with membrane vesicles has demonstrated an absolute dependence on K+ for proton translocation by the inorganic pyrophosphatase (H(+)-PPase: EC 3.6.1.1) from the vacuolar membrane (tonoplast) of higher plants. Using intact vacuoles from sugar beet (Beta vulgaris) storage tissue, we have monitored PP1-dependent currents by patch clamp in 'whole vacuole' mode. Serial K+ substitutions were made at both tonoplast faces. The results show that K+ activation occurs only at the cytosolic face.
authors.affiliation: Biology Department, University of York, UK.
authors.forename: J M
authors.initials: JM
authors.lastname: Davies
authors.forename: P A
authors.initials: PA
authors.lastname: Rea
authors.forename: D
authors.initials: D
authors.lastname: Sanders
mesh_terms: D001692:Biological Transport; D043564:Inorganic Pyrophosphatase; D008564:Membrane Potentials; D010944:Plants / Q000201:enzymology*; D011188:Potassium / Q000378:metabolism*; D011522:Protons; D011755:Pyrophosphatases / Q000378:metabolism*; D014617:Vacuoles / Q000502:physiology*
chemical_list: D011522:Protons; D011755:Pyrophosphatases; D043564:Inorganic Pyrophosphatase; D011188:Potassium