Figure 2. Downregulation of DC-SIGN and DC-SIGNR by viral proteins K3 and K5 is dependent on a functional RING-CH domain.

293 cells stably expressing DC-SIGN or DC-SIGNR were transfected with 4 µg of GFP-tagged expression constructs for wild-type K3 (K3 wt), wild-type K5 (K5 wt), RING-CH mutants (mZn) of each or empty vector. 36–48 hours post-transfection the cells were collected, stained for surface levels of DC-SIGN (A), DC-SIGNR (B) or endogenous MHC class I (A and B), as indicated and subjected to flow cytometry. Live cells were gated for GFP expression and the mean channel fluorescence (MCF) for each was calculated (inset numbers.) The data is representative of at least three experiments. C) Flow cytometry data presented in Panels A and B were quantified. The MCF value for each was normalized to vector cells. Error bars indicate standard deviations. The data presented are an average of three independent experiments.