InterPro domain: IPR006966

Peroxin 3 (Pex3p), also known as Peroxisomal biogenesis factor 3, has been identified and characterised as a peroxisomal membrane protein in yeasts and mammals [ 1 ]. Two putative peroxisomal membrane-bound Pex3p homologues have also been found in Arabidopsis thaliana [ 2 ]. They possess a membrane peroxisomal targeting signal. Pex3p is an integral membrane protein of peroxisomes, exposing its N- and C-terminal parts to the cytosol [ 2 ]. Peroxin is involved in peroxisome biosynthesis and integrity; it assembles membrane vesicles before the matrix proteins are translocated.

In humans, defects in PEX3 are the cause of peroxisome biogenesis disorders [ 3 ], which include Zellweger syndrome (ZWS), neonatal adrenoleukodystrophy (NALD), infantile Refsum disease (IRD), and classical rhizomelic chondrodysplasia punctata (RCDP). These are peroxisomal disorders that are the result of proteins failing to be imported into the peroxisome.

1. Sorting pathway and molecular targeting signals for the Arabidopsis peroxin 3. Biochem. Biophys. Res. Commun. 314, 586-96
2. The peroxin pex3p initiates membrane assembly in peroxisome biogenesis. Mol. Biol. Cell 11, 2085-102
3. PEX3 is the causal gene responsible for peroxisome membrane assembly-defective Zellweger syndrome of complementation group G. Am. J. Hum. Genet. 67, 976-81