Figure 3.
Effects of mutations in Nef from SIVmac239 on the internalization of CD4. (A) Internalization of CD4. Shown is the effect of mutations in Nef on CD4 down-regulation at steady state. Different Nef proteins and CD4 were coexpressed in 293-T cells. Levels of surface expression of CD4 [% CD4(+)] were evaluated by FACS. The surface expression of CD4 in the presence of CD8 alone (negative) was set to 100% and levels of CD4 in the presence of other hybrid mutant Nef proteins were calculated relative to this value. Error bars indicate SEMs of the mean from at least three independent experiments. (B) Levels of expression of Nef chimeras in 293-T cells. Levels of different Nef proteins were determined by Western blotting (lanes 2–11). They were compared with the endogenous actin.