Cell Biology

Making Membrane

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Science  01 Aug 2003:
Vol. 301, Issue 5633, pp. 567
DOI: 10.1126/science.301.5633.567c

Peroxisomes have been thought to represent autonomous intracellular organelles that metabolize lipids and drugs in oxidative reactions; the reactions generate H2O2 (which is disarmed by catalase), hence the appellation. Isolated peroxisomes can import peroxisomal proteins when added to cellular homogenates, and peroxisomes can proliferate when cells are challenged with a variety of inducers. However, it has not been altogether clear whether other intracellular organelles, such as the endoplasmic reticulum (ER), play a role in peroxisome biogenesis.

Geuze et al. used electron microscopy combined with immunocytochemistry and electron tomography to reconstruct three-dimensional images of peroxisomes in mouse dendritic cells. They found that several peroxisomal membrane proteins were present in specialized subdomains of the ER. The subdomain membranes were continuous with those of a peroxisomal reticulum—presumed to be the source of mature peroxisomes. Thus, although some peroxisomal proteins can be imported directly, peroxisomal membrane components may in large part be derived from the ER. — SMH

Mol. Biol. Cell 14, 2900 (2003).

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