Control of gastric H,K-ATPase activity by cations, voltage and intracellular pH analyzed by voltage clamp fluorometry in Xenopus oocytes.

ABSTRACT: Whereas electrogenic partial reactions of the Na,K-ATPase have been studied in depth, much less is known about the influence of the membrane potential on the electroneutrally operating gastric H,K-ATPase. In this work, we investigated site-specifically fluorescence-labeled H,K-ATPase expressed in Xenopus oocytes by voltage clamp fluorometry to monitor the voltage-dependent distribution between E(1)P and E(2)P states and measured Rb(+) uptake under various ionic and pH conditions. The steady-state E(1)P/E(2)P distribution, as indicated by the voltage-dependent fluorescence amplitudes and the Rb(+) uptake activity were highly sensitive to small changes in intracellular pH, whereas even large extracellular pH changes affected neither the E(1)P/E(2)P distribution nor transport activity. Notabl

SUBMITTER: Durr KL 

PROVIDER: S-EPMC3308979 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature