Fig. 3.

VIPER-tagged transferrin receptor retains transferrin binding and endocytosis. (A) CHO TRVb cells expressing TfR1-CoilE were treated with CoilR-Cy5 and fluorescent ligand (Tf-AF488). In live cells, labeling by both Tf-AF488 and CoilR-Cy5 was localized to the cell surface at 0 min. After 30 min, AF488 and Cy5 signals from the Tf-TfR1 complex were observed together in endocytic vesicles. (B) Cells expressing TfR1-mCherry were treated with Tf-AF488. In A and B, yellow boxes delineate Insets, which provide a 2× magnified view. The merged images (Right column) include Tf-AF488 (green), nuclear stain (blue), and either mCherry (magenta) or CoilR-Cy5 (magenta). (Scale bars: 25 μm.)