Fig. 1.

PSAP motif is essential for FIV particle egress, independently from an active viral protease. 293T (left panel) or CrFK (right panel) cells were transfected with different plasmids encoding FIV-Gag/Pol either wt (a) or characterised by a STOP codon in the Pol reading frame (b) and carrying the wt PSAP motif or a mutated L-domain, as indicated. Twenty-four h later, cell lysates (Cells) and virus like particles (VLPs) were analysed by western blotting; C-: transfection negative control. The bold arrows point to a partially processed form of Gag, most likely the MA-CA-p1-NC precursor.