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PEX19 is a predominantly cytosolic chaperone and import receptor for class 1 peroxisomal membrane proteins

Jacob M Jones1, James C Morrell, Stephen J Gould

  • 1Dept. of Biological Chemistry, The Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA.

The Journal of Cell Biology
|January 8, 2004
PubMed

Insights

PEX19 protein acts as a chaperone and import receptor, binding and stabilizing newly synthesized peroxisomal membrane proteins (PMPs). This reveals two distinct PMP import pathways.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Protein Trafficking

Background:

  • Integral peroxisomal membrane proteins (PMPs) are synthesized in the cytoplasm.
  • PMPs undergo post-translational import into peroxisomes.

Purpose of the Study:

  • To elucidate the role of PEX19 in PMP biogenesis.
  • To identify the mechanisms governing PMP targeting and import.

Main Methods:

  • In vitro binding assays to study PEX19 interactions.
  • Analysis of PMP targeting signals (mPTSs).
  • Investigating PEX19-dependent and independent import pathways.

Main Results:

  • PEX19 binds and stabilizes newly synthesized PMPs in the cytosol.
  • PEX19 interacts with multiple PMP targeting signals (mPTSs), particularly their hydrophobic domains.
  • Two distinct PMP import mechanisms were identified: PEX19-dependent (Class 1 mPTSs) and PEX19-independent (Class 2 mPTSs).

Conclusions:

  • PEX19 functions as a dual-role protein: a chaperone and an import receptor for PMPs.
  • The study reveals two distinct classes of mPTSs and their corresponding import pathways.
  • These findings advance the understanding of peroxisomal protein import and PEX19 function.

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