Article abstract
Nature Cell Biology 4, 134 - 139 (2002)
Published online: 28 January 2002 | doi:10.1038/ncb746
Protein dislocation from the ER requires polyubiquitination and the AAA-ATPase Cdc48
Ernst Jarosch1, Christof Taxis2, Corinna Volkwein1, Javier Bordallo2,4, Daniel Finley3, Dieter H. Wolf2 & Thomas Sommer1
Abstract
Endoplasmic reticulum (ER)-associated protein degradation by the ubiquitin–proteasome system requires the dislocation of substrates from the ER into the cytosol. It has been speculated that a functional ubiquitin proteasome pathway is not only essential for proteolysis, but also for the preceding export step. Here, we show that short ubiquitin chains synthesized on proteolytic substrates are not sufficient to complete dislocation; the size of the chain seems to be a critical determinant. Moreover, our results suggest that the AAA proteins of the 26S proteasome are not directly involved in substrate export. Instead, a related AAA complex Cdc48, is required for ER-associated protein degradation upstream of the proteasome.
- Max-Delbrück Center for Molecular Medicine, Robert-Rössle Strasse 10, 13092 Berlin, Germany
- University of Stuttgart, Institute for Biochemistry, Pfaffenwaldring 55, 70569 Stuttgart, Germany
- Harvard Medical School, Department of Cell Biology, 240 Longwood Avenue., Boston, Massachusetts 02115, USA
- Present address: Area de Farmacologia, Departmento de Medicina, C/ Julian Claveria s/n E-33006 Oviedo, Spain
Correspondence to: Thomas Sommer1 e-mail: tsommer@mdc-berlin.de
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