FIV Vif binding to CUL5 is zinc independent. (A and B) HEK293T cells were transfected with expression plasmids for FcaZ2bZ3-HA (A) or HsaA3G-HA (B), and HIV-1 Vif-V5, or FIV Vif-V5. pcDNA3.1 was used as the empty plasmid control. Transfected cells were treated with the zinc chelator TPEN (2, 3, 4, 5, 6, 7, or 8 μM) or DMSO as a control at 36 h posttransfection. Cells were harvested 12 h later (48 h after transfection) and then analyzed by immunoblotting with anti-HA, anti-V5, and antitubulin antibodies. (C) The myc-CUL5 expression plasmid was cotransfected with FIV Vif-V5 or HIV-1 Vif-V5 expression plasmids into HEK293T cells. The transfected cells were treated with 5 μM TPEN or DMSO at 36 h posttransfection. Cell lysates were immunoprecipitated with anti-myc beads and then analyzed by immunoblotting with anti-V5 antibody for FIV Vif and HIV-1 Vif and with anti-myc antibody for CUL5.