The protein translocation channel binds proteasomes to the endoplasmic reticulum membrane

Kai Uwe Kalies, Susanne Allan, Tatiana Sergeyenko, Heike Kröger, Karin Römisch*

*Corresponding author for this work
73 Citations (Scopus)


Misfolded secretory proteins are transported across the endoplasmic reticulum (ER) membrane into the cytosol for degradation by proteasomes. A large fraction of proteasomes in a cell is associated with the ER membrane. We show here that binding of proteasomes to ER membranes is salt sensitive, ATP dependent, and mediated by the 19S regulatory particle. The base of the 19S particle, which contains six AAA-ATPases, binds to microsomal membranes with high affinity, whereas the 19S lid complex binds weakly. We demonstrate that ribosomes and proteasomes compete for binding to the ER membrane and have similar affinities for their receptor. Ribosomes bind to the protein conducting channel formed by the Sec61 complex in the ER membrane. We co-precipitated subunits of the Sec61 complex with ER-associated proteasome 19S particles, and found that proteoliposomes containing only the Secol complex retained proteasome binding activity. Collectively, our data suggest that the Sec61 channel is a principal proteasome receptor in the ER membrane.

Original languageEnglish
JournalEMBO Journal
Issue number13
Pages (from-to)2284-2293
Number of pages10
Publication statusPublished - 06.07.2005


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