Pex3

Pex3, or peroxisomal biogenesis factor 3, is a protein essential for the formation and maintenance of peroxisomes in eukaryotic cells. It is an integral membrane protein localized to the peroxisomal membrane and is highly conserved across yeast, plants, and animals.

In the peroxisome biogenesis pathway, Pex3 serves as a docking platform for cytosolic chaperone–receptor complexes that ferry peroxisomal membrane proteins to the organelle. It interacts with Pex19, a cytosolic receptor for peroxisomal membrane proteins, and helps recruit these cargoes to the membrane. Pex3 also engages with other peroxins, such as Pex14 and Pex16, contributing to the organization and assembly of the peroxisomal protein import machinery. Through these interactions, Pex3 participates in both de novo formation of peroxisomes and the maintenance or proliferation of existing peroxisomes.

The protein is part of a conserved set of peroxins required for proper peroxisome biogenesis. In many organisms, loss or dysfunction of Pex3 disrupts peroxisome formation, leading to mislocalization or absence of peroxisomal enzymes and a failure to import matrix enzymes, with downstream cellular consequences. In humans, mutations in the PEX3 gene can contribute to peroxisome biogenesis disorders, such as Zellweger spectrum disorders, underscoring the protein’s essential role in cellular metabolism and organelle function.

Research on Pex3 spans genetics, cell biology, and structural studies. It highlights the importance of a coordinated membrane platform for peroxisome assembly and the integration of peroxisomal membrane protein trafficking with the broader protein import system of the organelle.