FIGURE 1:

Deletion of Ema19 leads to increased levels of nonimported mitochondrial precursor proteins. (A) A schematic representation of the Oxa1-Ura3 reporter assay is shown on the left. WT and Δema19 cells were transformed with empty (control) or Oxa1-Ura3 expression plasmids and grown on uracil-containing medium to mid-log phase. Serial 10-fold deletions were dropped onto glucose plates which contained or lacked uracil. The arrow depicts the efficient uracil-independent growth induced by Oxa1-Ura3 in Δema19 cells. (B) Schematic representation of the split-GFP assay. (C, D) WT and ∆ema19 cells expressing Sec63-GFP^1-10 and either Oxa1-GFP¹¹ or ΔN-Oxa1-GFP¹¹ were grown to mid-log phase before GFP-mediated fluorescence was measured. Values show mean and SD values from three measurements. (E) Microscopy pictures from the cells analyzed in D. Note that the GFP signal shows the characteristic perinuclear and cortical pattern of ER proteins in yeast cells. (F) Model for the accumulation of extramito­chondrial precursors in Δema19 cells.