Peroxisome biogenesis

It is considered most likely at present that peroxisomes are endoplasmic reticulum (ER)-derived organelles. The biosynthesis of peroxisomes in mammals involves three different processes, the formation of the pre-peroxisome from the ER, the import of the peroxisomal membrane and matrix proteins to the pre-peroxisome, and the growth and division of the peroxisome. Very recently a new process was reported, i.e. that pre-peroxisomes are formed by the fusion of vesicles derived from the ER and outer mitochondrial membranes. Based on recent findings, we discuss where the pre-peroxisomes are formed and become organized into mature peroxisomes. It is known that many proteins, called “peroxins”, are encoded by PEX genes and involved in peroxisome biogenesis, including the targeting of peroxisomal matrix and membrane proteins. To date, 36 peroxins have been identified. Here, recent progress in the mechanisms by which peroxisomal matrix and membrane proteins are targeted to the peroxisome are discussed. In addition, the selective targeting of ATP-binding cassette (ABC) transporter subfamily D to peroxisomes as well as lysosomes is also covered.