Peroxin

Peroxins are proteins essential for the biogenesis of peroxisomes. They are involved in a variety of processes, including the import of proteins into the peroxisome matrix, the formation of the peroxisomal membrane, and the proliferation of peroxisomes. The name "peroxin" is derived from peroxisome biogenesis factors.

Peroxins are typically integral membrane proteins or proteins associated with the peroxisomal membrane, though some reside in the cytosol and transiently interact with the peroxisome. They often form complexes that act as docking and import machinery for cargo proteins destined for the peroxisome matrix. These cargo proteins contain specific targeting signals, most commonly a peroxisomal targeting signal type 1 (PTS1) or type 2 (PTS2), which are recognized by specific peroxins (e.g., Pex5 for PTS1 and Pex7 for PTS2).

Different peroxins play distinct roles in peroxisome biogenesis. Some are involved in the initial formation of the peroxisomal membrane from the endoplasmic reticulum (ER), while others are necessary for the import of proteins into the peroxisome matrix after the membrane has formed. Still others are crucial for the division and proliferation of peroxisomes to maintain their numbers within the cell.

Mutations in genes encoding peroxins can lead to a group of genetic disorders called peroxisome biogenesis disorders (PBDs). These disorders are characterized by a failure to properly assemble functional peroxisomes, resulting in a wide range of neurological, developmental, and metabolic abnormalities. Examples of PBDs include Zellweger syndrome, neonatal adrenoleukodystrophy, and infantile Refsum disease. The specific symptoms and severity of PBDs can vary depending on which peroxin gene is mutated and the extent to which peroxisome function is impaired.