Fig. 4. Overexpression of Fab1p reverts the trafficking defects of apl2 and apl4 cells. (A) Overexpression of Fab1p in vac14 cells restores wild-type trafficking of GFP-CPS. vac14 cells were transformed with either empty plasmid, (YEplac181), or plasmid containing FAB1 (YEplac181-FAB1) as indicated, and plasmid expressing GFP-CPS (pUG34-CPS), and inspected by fluorescence and light microscopy. (B) GFP-CPS trafficking to the vacuole lumen is restored in apl2 and apl4 cells by overexpression of Fab1p. apl2 and apl4 cells were transformed with pUG34-CPS and empty plasmid (YCplac33) or a 2 µ plasmid containing FAB1 under its own promoter (pEMY105) (Cooke et al., 1998; Yamamoto et al., 1995) and inspected by fluorescence and light microscopy as indicated. Overexpression of Fab1p restored wild-type trafficking to approximately 50% of apl2 cells and to more than 90% of apl4 cells. (C) Overexpression of Fab1p had no effects in the vacuole morphology of apl2 and apl4 cells.