FIG. 1.

Vpu reduces BST-2 levels independently of the rate of endocytosis of BST-2. (A) HeLa cells were transfected with 1 μg of pEGFP-N1 with [Vpu(+)] or without [Vpu(−)] 1 μg of pcDNA-Vphu. The total DNA was adjusted to 5 μg with empty vector DNA. Cells were stained with BST-2 antibodies and analyzed with a FACSCalibur instrument. Samples were gated for GFP expression, which was used as a marker for transfected cells. As a control, HeLa cells were stained with preimmune serum (control). (B) Cells were transfected as described above for A, harvested 24 h after transfection, labeled at 4°C with antibody to BST-2, and then incubated at 37°C for the indicated times. Cells were then stained with a secondary antibody and analyzed with a FACSCalibur instrument. Samples were gated for GFP-positive cells. The mean fluorescence intensity of the time zero cells for each population was defined as 100% BST-2 surface expression. Plotted data were derived from five independent experiments. Error bars represent standard errors of the means.