Schematic illustration of the PFV Gag (PG) fusion expression constructs. CMV, cytomegalovirus virus promoter; SD, splice donor; SA, splice acceptor; pA, bovine growth hormone polyadenylation signal; L, glycine-serine linker. The p68/p71 PFV Gag cleavage site is shown as dashed line. PFV Gag fusion proteins were generated as N- or C-terminal fusions. The locations of the different protein tags (HA, eGFP, eYFP, mCherry, mCerulean) used are indicated as grey boxes (tag). The C-terminal PG CeGFP fusion protein was further modified by N-terminal fusion of a membrane-targeting signal (M) (PGM3).