title: Proteasome activators.
abstract: Proteasomes degrade a multitude of protein substrates in the cytosol and nucleus, and thereby are essential for many aspects of cellular function. Because the proteolytic sites are sequestered in a closed barrel-shaped structure, activators are required to facilitate substrate access. Structural and biochemical studies of two activator families, 11S and Blm10, have provided insights to proteasome activation mechanisms, although the biological functions of these factors remain obscure. Recent advances have improved our understanding of the third activator family, including the 19S activator, which targets polyubiquitylated proteins for degradation. Here we present a structural perspective on how proteasomes are activated and how substrates are delivered to the proteolytic sites.
authors.affiliation: Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112-5650, USA.
authors.forename: Beth M
authors.initials: BM
authors.lastname: Stadtmueller
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Hill
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D020536:Enzyme Activators / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D025821:Polyubiquitin / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D021122:Protein Subunits / Q000378:metabolism; D058767:Protein Unfolding; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism; D054875:Ubiquitination
chemical_list: D001426:Bacterial Proteins; D020536:Enzyme Activators; D021122:Protein Subunits; D029701:Saccharomyces cerevisiae Proteins; D025821:Polyubiquitin; D046988:Proteasome Endopeptidase Complex