The 26S proteasome, the central enzyme of the ubiquitin-proteasome system, is comprised of the 20S catalytic core particle (CP) and the 19S regulatory particle (RP), itself composed of two subcomplexes, the base and the lid. 20S proteasome assembly is assisted by several chaperones. Integral subunits of the RP participate in its assembly, but no external factors have been identified so far. Here we characterize the yeast Hsm3 protein, which displays unique features regarding 19S assembly. Hsm3 associates with 19S subcomplexes via a carboxy-terminal domain of the Rpt1 base subunit but is missing in the final 26S proteasome. Moreover, Hsm3 is specifically required for the base subcomplex assembly. Finally, we identify the putative species-specific 19S subunit S5b as a functional homolog of the Hsm3 chaperone in mammals. These findings shed light on chaperone-assisted proteasome assembly in eukaryotes.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Reference||Annotation Extension|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Conditions||Strain||Source||Reference|