Ca2+/H+ antiport activity in Arabidopsis root endomembrane vesicles. Pittman J K et al. J. Biol. Chem. 2002;277:26452-26459 ©2002 by American Society for Biochemistry and Molecular Biology Ca2+/H+ antiport activity in Arabidopsis root endomembrane vesicles. A, time course of 10 μm 45Ca2+ transport into Ca2+-treatedArabidopsis root endomembrane vesicles in the absence (closed circle) or presence (open circle) of 5 μm FCCP. Both treatments were performed in the presence of 200 μm vanadate. The Ca2+ ionophore A23187(5 μm) was added at 12 min. B, the effect of CAX1-NRR peptide concentration on ΔpH-dependent 10 μm Ca2+ transport into Ca2+-treated Arabidopsis root endomembrane vesicles measured at a 10-min time point. Results are shown following subtraction of the FCCP background values and shown as a percentage of Ca2+ uptake of the control sample in the absence of peptide. All results are the mean (±S.E.) of three independent experiments.