Fig. 5. ap3 promastigotes are defective in PPi- and ATP-dependent proton transport. (A,B) Proton-pumping activities visualised in permeabilised promastigotes loaded with Acridine Orange, upon addition of (A) 500 µM NaPP_i or (B) 1 mM ATP. 20 mM of NH₄Cl was added to reverse the proton gradient when indicated. The horizontal scales represent time and the vertical scales the absorbance variations of Acridine Orange at 530 nm and 493 nm following pH changes. Data shown are representative of three experiments performed with independent cultures.