Luminal and cytosolic pH feedback on proton pump activity and ATP affinity of V-type ATPase from Arabidopsis.

ABSTRACT: Proton pumping of the vacuolar-type H(+)-ATPase into the lumen of the central plant organelle generates a proton gradient of often 1-2 pH units or more. Although structural aspects of the V-type ATPase have been studied in great detail, the question of whether and how the proton pump action is controlled by the proton concentration on both sides of the membrane is not understood. Applying the patch clamp technique to isolated vacuoles from Arabidopsis mesophyll cells in the whole-vacuole mode, we studied the response of the V-ATPase to protons, voltage, and ATP. Current-voltage relationships at different luminal pH values indicated decreasing coupling ratios with acidification. A detailed study of ATP-dependent H(+)-pump currents at a variety of different pH conditions showed a complex reg

SUBMITTER: Rienmuller F 

PROVIDER: S-EPMC3308750 | biostudies-literature | 2012 Mar

REPOSITORIES: biostudies-literature