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Distinct requirements for intra-ER sorting and budding of peroxisomal membrane proteins from the ER

Gaurav Agrawal1, Scott N Fassas1, Zhi-Jie Xia1

  • 1Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093.

The Journal of Cell Biology
|February 3, 2016
PubMed

Insights

New research reveals how peroxisome proteins are sorted within the endoplasmic reticulum. Pex3 and Pex19 guide the budding of key importomer complexes, ensuring proper peroxisome assembly.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Peroxisome biogenesis requires the precise sorting of importomer complex proteins.
  • The mechanisms for segregating peroxisomal membrane proteins to the preperoxisomal endoplasmic reticulum (pER) and preperoxisomal vesicles (ppVs) remain unclear.

Purpose of the Study:

  • To elucidate the roles of Pex3 and Pex19 in the intra-endoplasmic reticulum (ER) sorting and budding of peroxisomal proteins.
  • To understand the segregation mechanisms of different peroxisomal importomer subcomplexes during biogenesis.

Main Methods:

  • Investigated protein interactions at the ER using co-immunoprecipitation and microscopy.
  • Analyzed the sorting and budding of peroxisomal proteins in response to genetic manipulations.
  • Utilized cell-based assays to track protein localization and complex formation.

Main Results:

  • Pex19 acts as a bridge between Pex3 and RING-domain peroxins (Pex2, Pex10, Pex12), forming a ternary complex essential for their intra-ER sorting and budding.
  • Docking subcomplex proteins (Pex13, Pex14, Pex17) require Pex19 for ER budding but sort independently of Pex3 and Pex19, segregating from RING-domain proteins.
  • Pex3 plays a distinct role in sorting Pex10 and Pex12 in conjunction with the docking subcomplex.

Conclusions:

  • A novel intra-ER sorting process regulates the segregation, packaging, and budding of peroxisomal importomer subcomplexes.
  • This process prevents the premature assembly of peroxisomal components within the ER, ensuring efficient de novo peroxisome biogenesis.

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