FIGURE 8.

TDH motif acts as an autonomous internalization signal. A, shown are representative COS-7 cells transfected with CD4 or the CD4-Kir2.3 chimeras (WT or mutant) at 0 and 5 min post-endocytic chase and after anti-CD4 antibodies were stripped from the cell surface. Scale bars = 10 μm. Accumulation of the surface-labeled chimera in endosomes was reduced to background levels by alanine replacement mutations in the di-hydrophobic motif. B, summary of the internalization data of CD4 and CD4-Kir2.3 chimeras, documenting the number of internalized antibody-labeled particles relative to the WT CD4-Kir2.3 chimera (mean ± S.E., n = 10; *, p < 0.05).