Figure 11.

Effect of MβCD on clathrin-coated pits and TfR distribution. (A) Examples of shallow coated pits characteristic of MβCD-treated cells and of immunogold labeling for TfRs in the coated pits. Arrowheads mark the extension of the pits. Asterisk marks for comparison a clearly noncoated vesicular profile. (B and C), Examples of TfR immunogold labeling of portions of the cell surface without coated pits and of microvilli (Mv). HEp-2 cells were incubated for 15 or 30 min at 37°C with 10 mM MβCD, fixed, incubated with B3/25 anti-TfR antibody and then with goat anti-mouse antibody conjugated to 10 nm gold, and processed for EM. Bar, 100 nm.