Multiple Pathways for Protein Transport to Peroxisomes

Abstract

Peroxisomes are unique among the organelles of the endomembrane system. Unlike other organelles that derive most if not all of their proteins from the ER ( endoplasmic reticulum), peroxisomes contain dedicated machineries for import of matrix proteins and insertion of membrane proteins. However, peroxisomes are also able to import a subset of their membrane proteins from the ER. One aspect of peroxisome biology that has remained ill defined is the role the various import pathways play in peroxisome maintenance. In this review, we discuss the available data on matrix and membrane protein import into peroxisomes.

Graphical Abstract

Highlights

• •

  Peroxisomal membrane and matrix proteins require distinct factors for their transport.

• •

  Matrix proteins fold in the cytosol prior to their import.

• •

  Loaded targeting receptors form part of the matrix protein translocation pore.

• •

  Many membrane proteins are directly inserted into the peroxisomal membrane.

• •

  Some peroxisomal membrane proteins are transported via the ER to peroxisomes.