Pex13

Pex13 is a peroxin, a peroxisomal membrane protein essential for peroxisome biogenesis and matrix protein import in eukaryotes, including yeast (Saccharomyces cerevisiae) and mammals. It is a component of the peroxisomal docking/translocation machinery that mediates the initial interaction between the cytosolic Pex5 receptor–cargo complex and the peroxisomal membrane import apparatus.

Structure and localization: Pex13 is an integral membrane protein embedded in the peroxisomal membrane, with regions facing the cytosol that participate in protein–protein interactions. In yeast, Pex13 interacts with other docking factors such as Pex14, forming a complex that facilitates cargo delivery. In many vertebrates, Pex13 proteins contain a cytosolic SH3 domain that contributes to binding partners involved in the import process.

Function: Pex13 participates in docking of Pex5–cargo complexes at the peroxisome and supports the import of peroxisomal matrix proteins. It works alongside Pex14 (and, in yeast, Pex17) as part of the docking complex, helping to coordinate receptor-cargo recognition with the translocation steps required for matrix protein import.

Biological significance: Disruption of Pex13 function impairs peroxisomal protein import and can affect peroxisome biogenesis or maintenance, leading to cellular deficiencies in peroxisomal metabolism. In humans, the PEX13 gene encodes the peroxisomal membrane protein, and defects in peroxin genes can contribute to peroxisome biogenesis disorders, though disease associations with PEX13 mutations are less frequently reported than for some other PEX genes.

See also: Peroxisome, Pex5, Pex14, Pex17, peroxin.