Figure 9.

Internalization of HRP by BWTG3 mock cells and cells producing BBMIΔ446 and BBMI-Tail. Cells were allowed to internalize HRP for 40 min at 37°C, fixed, and processed for DAB cytochemistry and conventional EM. In mock-treated cells (A) the electron-dense DAB reaction product was detected in intracellular compartments, which were morphologically related to endosomes (E) and lysosomes (L). In cells producing BBMIΔ446 (B), lysosomal-like compartments were devoid of electron-dense reaction product (arrows). In cells overexpressing BBMI-Tail (C), the reaction product accumulated in small vesicles distributed beneath the plasma membrane. Bars, 100 nm.