Barnase as a New Therapeutic Agent Triggering Apoptosis in Human Cancer Cells
Figure 4
Internalization of scFv 4D5-dibarnase into HER2-positive SKOV-3 cells demonstrated by electron microscopy.
SKOV-3 cells were incubated with 20 nM scFv 4D5-dibarnase-Au for 1 h at 4°C or at 37°C. (A and B) At 4°C, the gold label was deposited on the cytoplasmic membrane (m) and protrusions (asterisks) but not inside the cell. (C–H) At 37°C, scFv 4D5-dibarnase-Au bound to the cell surface in the same manner as at 4°C but was also found inside the cells in coated pits (cp) (D), coated vesicles (cv) (E), endosomes (e) (F and G), cytoplasm (c) (F and G, arrowheads), and multivesicular bodies (MVB) (H). The scFv 4D5-dibarnase-Au was not found in the nucleus (n) (F). Bar, 200 nm.