Mg2+/KCl-ATPase of plant plasma membranes is an electrogenic pump
AUTOR(ES)
Sze, Heven
RESUMO
The function of the Mg2+-requiring KCl-stimulated ATPase (ATP phosphohydrolase, EC 3.6.1.3) of higher plants in active ion transport was investigated by using a purified microsomal fraction containing sealed plasma membrane vesicles. (Sze, H. (1980) Proc. Natl. Acad. Sci. USA 77, 5904-5908). A transmembrane electrical potential (+30 to +44 mV), monitored by uptake of a permeant anion (35SCN-), was generated specifically by ATP in purified microsomal vesicles of tobacco callus. ATP-dependent 35SCN- uptake required Mg2+, was optimal at pH 6.75, and showed similar ATP concentration dependence as the Mg2+-requiring KCl-stimulated ATPase activity. Plasma membrane ATPase inhibitors (N,N′-dicyclohexylcarbodiimide and vanadate) inhibited generation of the ATP-dependent electrical potential. A proton conductor (carbonyl cyanide m-chlorophenylhydrazone), but not a K+ ionophore (valinomycin), completely collapsed the electrical potential. The results provide in vitro evidence that the Mg2+/KCl-ATPase of higher plants is an electrogenic pump. These results are consistent with the hypothesis that an electrogenic H+ pump is catalyzed by the plasma membrane ATPase of plants.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=348793Documentos Relacionados
- The neurospora plasma membrane ATPase is an electrogenic pump.
- Evidence for a Cl−-Stimulated MgATPase Proton Pump in Oat Root Membranes 1
- Glutathione disulfide-stimulated Mg2+-ATPase of human erythrocyte membranes.
- Is the red cell calcium pump electrogenic?
- A plant plasma membrane Ca2+ pump is required for normal pollen tube growth and fertilization
