Cell Biology

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Science  26 Mar 2004:
Vol. 303, Issue 5666, pp. 1947-1949
DOI: 10.1126/science.303.5666.1947d

The peroxisome is a membrane-bound organelle involved in lipid and drug metabolism. The protein constituents of the peroxisome are synthesized in the cytosol and must be imported into peroxisomes. One group of peroxisomal membrane proteins is known as the class I proteins, and their import into the peroxisome is facilitated by a chaperone protein, PEX19, which binds newly synthesized peroxisomal class I membrane proteins in the cytosol and ferries them to the peroxisome.

Fang et al. have identified a protein, PEX3, which plays an essential role in this process by acting as a docking factor on the peroxisomal membrane for PEX19-carried import substrates. In the absence of PEX3, class I peroxisomal membrane proteins cannot enter peroxisomes, whereas class II peroxisomal membrane proteins and matrix proteins are still imported efficiently. — SMH

J. Cell Biol. 164, 863 (2004).

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