The BioGRID | PUBLICATION VIEW

	PLoS Biol. Aug (2006); 4(8):e267
Structural organization of the 19S proteasome lid- insights from MS of intact complexes-
Sharon M, Taverner T, Ambroggio XI, Deshaies RJ, Robinson CV
Department of Chemistry, University of Cambridge, Cambridge, United Kingdom-
Abstract: 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-
[PUBMED: 16869714]