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Mol Cell Biol. 2009 Oct;29(20):5505-16. doi: 10.1128/MCB.00388-09. Epub 2009 Aug 17.

Pex2 and pex12 function as protein-ubiquitin ligases in peroxisomal protein import.

Author information

1
Institut für Physiologische Chemie, Ruhr-Universität Bochum, Universitätsstr. 150, D-44780 Bochum, Germany.

Abstract

The PTS1-dependent peroxisomal matrix protein import is facilitated by the receptor protein Pex5 and can be divided into cargo recognition in the cytosol, membrane docking of the cargo-receptor complex, cargo release, and recycling of the receptor. The final step is controlled by the ubiquitination status of Pex5. While polyubiquitinated Pex5 is degraded by the proteasome, monoubiquitinated Pex5 is destined for a new round of the receptor cycle. Recently, the ubiquitin-conjugating enzymes involved in Pex5 ubiquitination were identified as Ubc4 and Pex4 (Ubc10), whereas the identity of the corresponding protein-ubiquitin ligases remained unknown. Here we report on the identification of the protein-ubiquitin ligases that are responsible for the ubiquitination of the peroxisomal protein import receptor Pex5. It is demonstrated that each of the three RING peroxins Pex2, Pex10, and Pex12 exhibits ubiquitin-protein isopeptide ligase activity. Our results show that Pex2 mediates the Ubc4-dependent polyubiquitination whereas Pex12 facilitates the Pex4-dependent monoubiquitination of Pex5.

PMID:
19687296
PMCID:
PMC2756880
DOI:
10.1128/MCB.00388-09
[Indexed for MEDLINE]
Free PMC Article
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