Figure 5.

Immunogold electron microscopy of Syn7 and Vamp 8 associated with rat liver late endosomes, lysosomes, and hybrid organelles. Immunoelectron microscopy of Syn7 (A–C) labeling with the use of rabbit anti-Syn7#1 (15-nm gold; large arrowheads), Vamp 8 (E–G) labeling (15-nm gold; large arrowheads), and internalized ASF-avidin (A, B, E, and G) (8-nm gold; small arrowheads) associated with rat liver late endosomes (A and E), hybrid organelles (B and F), and lysosomal fractions (C and G). Late endosomes and hybrid organelles were identified by their content of ASF–avidin. Lysosomes were identified by their electron-dense morphology. Bar, 200 nm. (D and H) Quantitation of the level of Syn7 labeling (D) and Vamp 8 labeling (H) on the peripheral membrane of late endosomes (le; 30 μm scored), hybrid organelles isolated after late endosome–lysosome fusion in the cell-free fusion system (h; 65 μm scored), and lysosomes isolated after incubation with cytosol and ATP under the conditions of the cell-free fusion system (ly; 1000 μm scored). Error bars represent SEM for the number of organelles scored.