FIG 2.

Nef and Vpu affect the cell surface levels of TSPANs and show a distinct pattern of TSPAN downmodulation. A3.01 T lymphocytes were transiently transfected with the expression plasmids for GFP fusions of Nef or Vpu, unrelated proteins with properties similar to those of Nef or Vpu (N18.src and pDisplay, respectively) (pDisplay as YFP fusion) (A), the indicated Nef (B) and Vpu (C) mutant proteins, or the GFP control. Forty-eight hours later, cells were stained for flow cytometry analysis with selected antibodies for cell surface markers by indirect immunofluorescence. Receptor levels of GFP-positive cells were compared with those of untransfected cells within individual samples (Fig. 1). Shown are arithmetic mean values and standard errors of the means from three (two in the cases of Nef G2A, Δ12-39, and VGFAAA) experiments in triplicates.