PEX5 and PEX7 bind peroxisome targeting signals (PTS) to traffic proteins from the cytosol to the peroxisome matrix. PEX5 binds the canonical sequence, PTS1, and PEX7 binds the non-canonical PTS2 sequence. No peroxisomal PTS2-containing protein has been identified in Drosophila, but Pex7 can functionally replace human Pex7 as a PTS2 receptor (FBrf0241151).

There is debate as to whether PEX5 is a substrate for import or is an integral part of the import translocon (PMID:36117327).