peroxisomessmall

Peroxisomes are small, single-membrane-bound organelles found in most eukaryotic cells. They are typically 0.3 to 1.0 micrometers in diameter and appear dispersed in the cytoplasm. The peroxisomal matrix houses a variety of enzymes, and the organelles import many of their proteins through specific targeting signals.

Functions of peroxisomes include lipid metabolism, detoxification, and synthesis of important cellular components. They participate in the beta-oxidation of very long-chain and branched-chain fatty acids, helping to shorten fatty acids for use by other parts of the cell. They contain catalase and other enzymes that break down hydrogen peroxide and manage reactive oxygen species. Peroxisomes also contribute to the biosynthesis of plasmalogens, a type of ether phospholipid important for membrane integrity, particularly in nervous and cardiovascular tissues. In the liver and other tissues, they participate in bile acid precursor metabolism and other specialized lipid pathways.

Biogenesis and dynamics involve peroxisome growth and division, which can arise from existing peroxisomes, or de novo from precursor membranes such as the endoplasmic reticulum. Peroxins (PEX proteins) recognize targeting signals, such as PTS1 and PTS2, to import matrix enzymes. Peroxisome numbers and function can adapt to cellular metabolic needs.

Clinical relevance centers on peroxisomal disorders. Defects in peroxisome biogenesis or in single-peroxisomal enzymes cause peroxisome biogenesis disorders, including Zellweger spectrum disorders. These conditions can feature hypotonia, developmental delay, liver dysfunction, and accumulation of very long-chain fatty acids. Management is supportive, and research continues to clarify disease mechanisms and potential therapies.

Overall, peroxisomes play essential roles in lipid processing and cellular detoxification, contributing to metabolic balance and membrane formation across many cell types.