Inhibiting dynamin-1 or clathrin assembly prevents CTR1 endocytosis: imaging analysis. CTR1 endocytosis was prevented in HEK-CLIP–CTR1 cells expressing dominant-negative DynK44A–HA (D) or AP180c–FLAG (B), but not in cells transfected with control empty vector (A) or expressing wild-type dynamin-1 (DynWT, C). Surface CTR1 proteins were fluorescently labeled with CLIP-Surface label (CTR1), and then cells were treated with Tf and 30 µM Cu for 30 min. Cells were fixed and probed with anti-TfR and either anti-FLAG or anti-HA antibodies. Confocal images at 100× are displayed, and 4× zoomed sections are shown in far right panels. Asterisks indicate cells that contain exogenous expression of dynamin or AP180c. CTR1 and TfR merge is displayed in yellow. Scale bars: 20 µm in first four columns, 10 µm in far right column.