Figure 3.

Inhibition of IFN-α-induced phosphorylation of STAT2 in the presence of C protein. U6A cells in a 35-mm dish were transfected with an expression vector for FL-STAT2 (1 μg) or FL-STAT2ΔN (1 μg) together with an expression vector for FL-C (0.4 μg) (A) or FL-Y3 (1 μg) (B). At 24 h post-transfection, the cells were stimulated with IFN-α (1,000 units/ml) for 1 h. C, U3A cells were transfected with an expression vector for FL-STAT2 together with an expression vector for FL-C or FL-Y3. At 24 h post-transfection, the cells were stimulated with IFN-α (1,000 units/ml) for 1 h. Proteins in the cell extracts were separated by SDS-PAGE for Western blot analysis using an anti-Tyr⁶⁹⁰-phosphorylated STAT2 antibody (Anti-pSTAT2) and anti-FL. D, the rate of phosphorylation inhibition was determined on the basis of averaged signal intensity of FL-STAT2 in A–C, which was calculated from three independent experiments. Signal intensity of FL-STAT2 was used as an internal standard.