Fig. 4
Effect of quadruple– and triple–alanine substitution mutants of Vif on CBFβ interaction and A3G degradation. Comparison of selected double, quadruple– (5WQVM8 > 4A), and triple– (9IVW11 > 3A) alanine substitution mutants of Vif with respect to CBFβ binding, A3G degradation, and ability to rescue virus infectivity. a Representative immunoblots of cell lysates (upper three panels) and co-IP (lower panel) probed for Flag-CBFβ, Vif, and tubulin (loading control) are shown. b Average efficiency with which Vif mutants bind to CBFβ from two independent transfection experiments relative to WT Vif (set to 100%). Statistical significance was determined using t test; *P < 0.05. c A representative immunoblot showing the effect of Vif mutants on A3G degradation. d Quantitation of relative A3G levels compared to the no Vif control (set to 100%). Error bars indicate standard deviations from four independent experiments. Statistical significance was determined using t test; *P < 0.05. e Infectivity of viruses produced in 293T cells in the presence of Flag-A3G and the indicated Vif mutants; mean ± SDs are for virus stocks obtained from two independent transfection experiments; virus infectivity of each virus stock was an average of three infections. All comparisons were based on viruses produced in the presence of WT Vif (set to 100%). Statistical significance was determined using t test; *P < 0.05