Table 2.

The Intracellular Part of ErbB2 Is Degraded by Proteasomal Activity in Clathrin-Depleted Cells

Labeling Intensity (% of Control)
Antibodye.c.*i.c.
Geldanamycin78.29.1
Lactacystin + geldanamycin85.690.8
  • NOTE: SKBr3 cells transfected with siRNA to CHC were preincubated with or without lactacystin (10 μmol/L) for 1 h before geldanamycin (3 μmol/L) was added for 6 h. The cells were then prepared for immunoelectron microscopy and labeled with antibody e.c.* recognizing the extracellular part of ErbB2 or antibody i.c. recognizing the intracellular part of ErbB2. The labeling for ErbB2 at the plasma membrane was quantified as gold particles per unit length of plasma membrane of 10 cell profiles for each experimental condition. The results are presented as percentage of the labeling density found for each antibody in control cells transfected with siRNA to CHC, but not incubated with lactacystin or geldanamycin.