Fig. 1.

Alkalinization of the DV by the V-type H⁺-ATPase inhibitor concanamycin A. (A and B) Representative fluorometer traces showing the alkalinization of the DV following the addition of concanamycin A (100 nM, at the point indicated by the black triangle) to isolated mature trophozoite-stage CQS D10^C (A) and CQR D10^7G8 (B) parasites suspended in the presence (gray traces) or absence (solvent control; black traces) of 2.5 μM CQ. CQ was added 4 min before the addition of concanamycin A. (C) Effect of increasing external CQ concentrations on the rate of DV alkalinization (expressed as the inverse of the half-time) following H⁺-ATPase inhibition in the pfcrt-modified clones. CQ was added to saponin-isolated mature trophozoites containing fluorescein-dextran in their DVs 4 min prior to the addition of concanamycin A (100 nM). Data are averaged from at least three separate experiments for each line and are shown as means ± SEM. For clarity, only positive error bars are shown for the 3D7^C, 3D7^7G8, GC03^C, and C6^7G8 lines, and only negative error bars are shown for the D10^C, D10^7G8, and GC03^7G8 lines. Where not shown, error bars fall within the symbols.