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Protein import into peroxisomes

Published on May 28, 2026   12 min

A selection of talks on Cell Biology

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0:00
Welcome, everybody. My name is Michael Schrader. I'm a professor of cell biology in the Department of Biosciences at the University of Exeter. In my short talk, I would like to explain protein import into peroxisomes.
0:19
Peroxisomes are ubiquitous organelles. We can find them in almost all eukaryotic cells. They fulfill very important functions in cellular lipid metabolism and in cellular redox balance. Peroxisomes in mammalian cells contain over 230 proteins, which need to be targeted to the organ. The peroxisomal lumen or so-called matrix is enclosed by a single limiting membrane. Peroxisomes do not contain DNA, therefore all peroxisomal proteins are encoded in the nucleus and are translated on free ribosomes in the cytoplasm. The proteins then need to be post-translationally transported to the organelle membrane or matrix. This requires distinct transport machineries for matrix and membrane protein import. There are a few examples. Some peroxisomal membrane proteins may be targeted via the endoplasmic reticulum.
1:27
The molecular transport machineries are composed of peroxins. These are proteins essential for the biogenesis of peroxisomes and are encoded by PEX genes. They are all numbered according to their discovery, and currently more than 37 peroxins have been identified across eukaryotes. They are usually membrane proteins or membrane-associated. The majority of them mediate matrix protein import. Three proteins, PEX19, 3, and 16, are required for membrane assembly and membrane protein import. PEX11 is involved in the proliferation and multiplication of peroxisomes, and dysfunctions in these peroxins can lead to severe peroxisome biogenesis disorders.

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