FIGURE 9.

Surface fluorescence of mutated E3/49K is lost in the absence of any internalization, whereas WT E3/49K is internalized. A549 cells stably expressing either WT, YA/LLAA mutant, or ΔCT truncated E3/49K were surface-labeled on ice with E3/49K N-terminal mAb 4D1. Excess antibody was removed, and then cells were warmed to 37 °C and incubated for the times indicated. Upon fixation, the location of prebound antibody was then revealed by staining with secondary antibody and imaged as in Fig. 2G using the same settings throughout to ensure comparability of image intensity. Scale bar, 25 μm. One representative experiment of at least two is shown.