Figure 4.

Analysis of isolated phagosomes. Phagosomes containing either A. felis, B. pertussis TIΔtox, or L. innocua, or a pseudophagosome fraction (not infected) from uninfected macrophages were isolated as described in Materials and Methods. (A) Samples were processed for electron microscopy (L. innocua, magnification ×10,000; A. felis, ×24,000). Phagosome membranes are marked by arrowheads and a free longitudinally cut Listeria by an arrow. (B) Phagosomal protein was analyzed by Western blot analysis by using antibodies to organelle marker proteins (see Materials and Methods). *, immature and intermediate 48- to 51-kDa precursor forms of cathepsin D (cath D); **, mature form (31 kDa). Either 2 or 40 μg protein of the PNS fractions or 2 μg protein of each phagosomal fraction were analyzed. Acronyms and sources of antibodies are listed in Materials and Materials. Each result is representative for at least three independent experiments.