Figure 1

ATP consumption by phagosomal preparations. Phagosomal preparations were incubated al 20°C with γ32P.ATP in the presence of different concentrations of unlabelled ATP and with the addition (when indicated) of 10 mM KF + 1 mM orthovanadate (F + V). Lipids and proteins were separated by a chloroform:methanol extraction and the water soluble radioactive species were resolved by TLC. A. A typical TLC plate showing the time dependent ATP hydrolysis. Left most lane: γ32P.ATP (5X concentration) before adding to the phagosomal preparation. Right most lane: same γ32P.ATP aliquot incubated with 10 U/ml apyrase. B. The TLC plate of a typical experiment as shown in A was scanned and the percentage of non hydrolyzed γ32P.ATP was estimated. Experimental data are plotted as symbols; the model predictions as solid lines having the same colours than the corresponding experimental observations.