FIG. 4.

Mechanism of K22, SLV, K26, and K34 residues in regulating Vif function. (A and B) Interaction of Vif mutants with A3F or A3G. The indicated Vif proteins were coexpressed with GFP, A3F, or A3G protein with a FLAG-HA tag in 293T cells. The proteins were pulled down by anti-FLAG antibody-conjugated beads and analyzed by Western blotting. Membranes were first incubated with a polyclonal anti-Vif antibody to detect Vif proteins and then an anti-HA antibody to detect GFP, A3F, and A3G proteins. (C) A3F and A3G expression in virus producer cells and virions. The indicated HIV-1 strains bearing vif mutations were produced from 293T cells in the presence of A3F or A3G protein expression. Protein expression in cells and purified virions was determined by Western blotting. A3F and A3G were detected by an anti-V5 antibody, Vif was detected by a polyclonal antibody, and Gag was detected by a monoclonal antibody.