tRNAPro incorporation into HIV-1 VLPs produced in murine cells. (A) 2D PAGE resolution of tRNAs in VLPs produced from GM11686 cells. VLPs are produced from vGag-4CTE (panel 1), vGag/GagPol-4CTE (panel 2), hGag (panel 3), and hGag/hGagPol (panel 4). (B, left) Western blots of the expression in GM11686 cells and the extracellular production of hGag and C-terminally deleted hGag (Δ378-500). (Right) 2D PAGE of tRNA extracted from hGag and hGag (Δ378-500) VLPs produced from GM11686 cells. (C) 2D PAGE resolution of tRNAs in HIV-1 hGag/hGagPol VLPs and in MuLV produced in transiently transfected murine A9 cells, the parent cell of GM11686, and lacking human chromosome 2. VLPs are produced from hGag (panel 7), hGag/hGagPol (panel 8), and hGag (Δ378-500) (panel 9), which is expressed in the cell but does not form extracellular VLPs (panel 7). The 2D PAGE pattern of tRNAs in MuLV (panel 10) is also shown.