Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published August 2006 | Published
Journal Article Open

Structural Organization of the 19S Proteasome Lid: Insights from MS of Intact Complexes


The 26S proteasome contains a 19S regulatory particle that selects and unfolds ubiquitinated substrates for degradation in the 20S catalytic particle. To date there are no high-resolution structures of the 19S assembly, nor of the lid or base subcomplexes that constitute the 19S. Mass spectra of the intact lid complex from Saccharomyces cerevisiae show that eight of the nine subunits are present stoichiometrically and that a stable tetrameric subcomplex forms in solution. Application of tandem mass spectrometry to the intact lid complex reveals the subunit architecture, while the coupling of a cross-linking approach identifies further interaction partners. Taking together our results with previous analyses we are able to construct a comprehensive interaction map. In summary, our findings allow us to identify a scaffold for the assembly of the particle and to propose a regulatory mechanism that prevents exposure of the active site until assembly is complete. More generally, the results highlight the potential of mass spectrometry to add crucial insight into the structural organization of an endogenous, wild-type complex.

Additional Information

© 2006 Sharon et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Received: March 31, 2006; Accepted: June 9, 2006; Published: August 1, 2006 M.S. is grateful for funding from the European Molecular Biology Organization and from the Wingate Scholarship. We thank Rati Verma and Sarah Maslen for valuable assistance in the preparation of this manuscript. CVR acknowledges the Walters-Kundert trust. Author contributions: MS, RJD, and CVR conceived and designed the experiments. MS and TT performed the experiments. MS and TT analyzed the data. XIA and RJD contributed reagents/materials/analysis tools. MS, RJD, and CVR wrote the paper. Competing interests: The authors have declared that no competing interests exist.

Attached Files

Published - SHAplosbio06.pdf


Files (2.1 MB)
Name Size Download all
2.1 MB Preview Download

Additional details

August 22, 2023
October 23, 2023