Involved in peroxisome biogenesis and the import of peroxisomal matrix proteins that contain the peroxisomal targeting sequence PTS2. Required for peroxisomal targeting of PEX7 and growth on oleate. Interacts with PEX7 and PEX13. The interaction with PEX7 stabilizes PEX18. Ubiquitinated in a UBC4/UBC5 dependent manner.