Figure 5. Distribution of H⁺-ATPase activity from epimastigotes on sucrose density gradients.

ATP-dependent bafilomycin A₁ (0.5 μM)-insensitive proton transport activity (C) is concentrated in fractions B1 and B2. Its distribution was compared with that of established organelle markers: acid phosphatase (lysosomes); hexokinase (glycosomes); succinate cytochrome c reductase (mitochondria), and vacuolar proton pyrophosphatase (V-H⁺-PPase, acidocalcisomes). Scale bars show mean±S.E.M. as percentage of total recovered activity (or total activity for H⁺-transport (C) in absorbance/min per mg protein from 4 experiments. (B) Western blot analysis showing that cruzipain (CRZPN), which concentrates in reservosomes and lipopeptidephosphoglycan (LPPG, a plasma membrane marker) are in the different fractions of the gradient. Anti-cruzipain reactivity is present in fractions B1 and B2 whereas LPPG reactivity is absent in these fractions.