FIG 5.

The responsive residue determines the ability of FIV Vif to degrade feline A3. (A) Schematic depicting the FIV Vif derivatives used. (B and C) Expression plasmids for a series of FIV Vif derivatives tagged with Flag were cotransfected with or without the expression plasmids for feline A3Z2Z3 (B) or A3Z3 (C) tagged with HA. Representative results of Western blotting assays are shown. (D) VESPA analysis. The percent amino acid sequence conservation was analyzed using VESPA (http://www.hiv.lanl.gov/content/sequence/VESPA/vespa.html) (34). The accession numbers of the FIV Vif sequences (subtype A, n = 5; subtype B, n = 8; subtype C, n = 10; subtype D, n = 4) are listed in Table 1. In the bottom panel, residues 167 and 242 to 243 are indicated in red, while the (T/S)LQ motif (residues 200 to 202) is indicated in blue. In the top panel, the amino acids in these positions are indicated as logo plots. n, the number of sequences used.