Pex5p imports folded tetrameric catalase by interaction with Pex13p

Traffic. 2012 Oct;13(10):1364-77. doi: 10.1111/j.1600-0854.2012.01391.x. Epub 2012 Jul 29.


Human catalase forms a 240-kDa tetrameric complex and degrades H(2) O(2) in peroxisomes. Human catalase is targeted to peroxisomes by the interaction of its peroxisomal targeting signal type 1 (PTS1)-like KANL sequence with the cytosolic PTS1 receptor Pex5p. We show herein that human catalase tetramers are formed in the cytoplasm and that the expression of a PTS signal on each of the four subunits is not necessary for peroxisomal transport. We previously demonstrated that a Pex5p mutant defective in binding to Pex13p, designated Pex5p(Mut234), imports typical PTS1-type proteins but not catalase. This impaired catalase import is not rescued by replacing its C-terminal KANL sequence with a typical PTS1 sequence, SKL, indicating that the failure of catalase import in Mut234-expressing cells is not due to its weak PTS1. In contrast, several enzymatically inactive and monomeric mutants of catalase are efficiently imported in Mut234-expressing cells. Moreover, trimeric chloramphenicol acetyltransferase (CAT) harboring SKL is not imported in Pex5p(Mut234)-expressing cells, but CAT-SKL trimers are transported to peroxisomes in the wild-type cells. These findings suggest that the Pex5p-Pex13p interaction likely plays a pivotal role in the peroxisomal import of folded and oligomeric proteins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Animals
  • CHO Cells
  • Catalase / chemistry
  • Catalase / genetics
  • Catalase / metabolism*
  • Chloramphenicol O-Acetyltransferase / metabolism
  • Cricetinae
  • Cricetulus
  • Humans
  • Membrane Proteins / metabolism*
  • Mutation
  • Peroxisome-Targeting Signal 1 Receptor
  • Peroxisomes / metabolism*
  • Protein Folding
  • Protein Sorting Signals
  • Protein Structure, Quaternary
  • Protein Transport
  • Receptors, Cytoplasmic and Nuclear / chemistry
  • Receptors, Cytoplasmic and Nuclear / genetics
  • Receptors, Cytoplasmic and Nuclear / metabolism*


  • Membrane Proteins
  • Peroxisome-Targeting Signal 1 Receptor
  • Protein Sorting Signals
  • Receptors, Cytoplasmic and Nuclear
  • Catalase
  • Chloramphenicol O-Acetyltransferase