We have cloned PEX15 which is required for peroxisome biogenesis in Saccharomyces cerevisiae.

Abstract. We identified a Saccharomyces cerevisiae peroxisomal membrane protein, Pexl3p, that is essential for protein import. A point mutation in the COOHterminal Src homology 3 (SH3) domain of Pexl3p inactivated the protein but did not affect its membrane targeting. A two-hybrid screen with the SH3 domain of Pexl3p identified Pex5p, a receptor for proteins with a type I peroxisomal targeting signal (PTS1), as its ligand.Pexl3p SH3 interacted specifically with Pex5p in vitro. We determined, furthermore, that Pex5p was mainly present in the cytosol and only a small fraction was associated with peroxisomes. We therefore propose that Pex13p is a component of the peroxisomal protein import machinery onto which the mobile Pex5p receptor docks for the delivery of the selected PTS1 protein.