Peroxisomes are cytoplasmic organelles enclosed by a single membrane and with a granular matrix, sometimes with a crystalline core. They carry various enzymes, particularly oxidases, used in both catabolic and anabolic pathways. Peroxisomes play an important role in lipid metabolism by carrying out fatty acid oxidation and synthesis of ether phospholipids. They are also responsible for the metabolism of toxic reactive oxygen species (ROS) generated within the cell, thus regulating cellular redox balance. In recent years, research has also revealed a role for peroxisomes in cell signaling, cellular stress response, and as protection against pathogens. Peroxisomes are dynamic and versatile organelles. Their numbers, size, morphology and activities are modified in response to various cellular and environmental signals, and in close communication and coordination with particularly the ER, lipid droplets and mitochondria.
Peroxisomes are ubiquitous and can be found spread throughout the cell, but their numbers and size vary between cell types and conditions. Also, their shape varies from round to more elongated. Differentiation between different types of vesicles in the endomembrane system requires co-staining with marker dyes or of marker proteins. Therefore, vesicle-like stainings are annotated as "vesicles" in the subcellular section, while the terms "endosomes", "lysosomes" and "peroxisomes" are only used if colocalization experiments have been carried out.
Read more about the proteome of peroxisomes as a substructure of vesicles.