FIG. 9.

Pex18p binds Fox3p only via Pex7p. (A) Fox3p was tested in a two-hybrid assay for interaction with Pex18p (upper panel) and Pex7p (lower panel) in the HF7c wild type as well as the pex18Δ pex21Δ and pex7Δ strains. (B) Binding of Pex7p to a synthetic PTS2 protein in vitro. Equal amounts of MBP-Pex7p were loaded onto affinity columns and incubated with soluble extracts of bacterially expressed GST-PTS2-GFP-prA (GST-PTS2; right lane in each panel) or GST (left lane). The right panel shows a Coomassie blue stain of the loaded fractions. The retention of GST-containing proteins was analyzed by immunoblotting (upper-left panel). The lower panel shows the presence of MBP-Pex7p in both eluates. (C) Coimmunoprecipitation of Fox3p with Pex18p. Strains pex7D PEX18-TAP (yAS3), pex21D PEX18-TAP (yAS4), and the untransformed UTL7-A wild type were induced in oleic acid-containing medium and analyzed for the presence of Pex7p and Fox3p in the precipitate of Pex18p-TAP by immunoblotting (upper panel). The upper and lower panels show 33% of the immunoprecipitated samples and 0.2% of the total cell lysates, respectively.