FIGURE 4.

Binding activity of chimeric Vif proteins to APOBEC3G. A, 293T cells were cotransfected with the T7 epitope-tagged APOBEC3G expression plasmid, Rev expression plasmid, and RRE-carrying/FLAG-tagged chimeric Vif expression plasmids were immunoprecipitated (IP) with an anti-FLAG monoclonal antibody. The resulting complexes were analyzed by immunoblotting with monoclonal antibodies to the T7 epitope or with polyclonal antibodies to FLAG to detect APOBEC3G and Vif proteins, respectively (upper two panels in each experiment). Cell lysate aliquots were also analyzed by immunoblotting in parallel for T7 epitope and FLAG together with β-actin (lower three panels). Results of three independent experiments are individually shown as Experiments 1, 2, and 3. B, binding activity of chimeric Vif proteins to APOBEC3G was quantified based on the band intensity of the immunoprecipitated APOBEC3G protein. Results are the mean ± S.D. of three experiments. *, p < 0.01; **, p < 0.001, t test.