Mutant pex5Δ cells or ubp15Δpex5Δ cells were transformed with plasmids expressing Pex5p or indicated variants. (A) Whole-cell lysates of oleic acid-induced strains as indicated were subjected to immunoblot analysis with Pex5p-specific antibodies. Mitochondrial Porin served as control for equal loading. (B) Signal intensities of Pex5p of three independent experiments were estimated by densitometry. Obtained signal intensities were normalized to signal from plasmid-encoded wild-type Pex5p expressed in pex5Δ cells. The steady-state concentration of Pex5p_C6K and especially Pex5p_{C6K/K18R/K24R} was drastically reduced in the absence of Ubp15p. Error bars=S.E.M.