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Vacuolar proton-pumping pyrophosphatase in Beta vulgaris shows vectorial activation by potassium
J M Davies1, P A Rea, D Sanders
1Biology Department, University of York, UK.
FEBS Letters
|January 14, 1991
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.