title: Proteasome-associated proteins: regulation of a proteolytic machine.
abstract: The proteasome is a compartmentalized, ATP-dependent protease composed of more than 30 subunits that recognizes and degrades polyubiquitinated substrates. Despite its physiological importance, many aspects of the proteasome's structural organization and regulation remain poorly understood. In addition to the proteins that form the proteasome holocomplex, there is increasing evidence that proteasomal function is affected by a wide variety of associating proteins. A group of ubiquitin-binding proteins assist in delivery of substrates to the proteasome, whereas proteasome-associated ubiquitin ligases and deubiquitinating enzymes may alter the dynamics of ubiquitin chains already associated with the proteasome. Some proteins appear to influence the overall stability of the complex, and still others have the capacity to activate or inhibit the hydrolytic activity of the core particle. The increasing number of interacting proteins identified suggests that proteasomes, as they exist in the cell, are larger and more diverse in composition than previously assumed. Thus, the study of proteasome-associated proteins will lead to new perspectives on the dynamics of this uniquely complex proteolytic machine.
authors.affiliation: Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA.
authors.forename: Marion
authors.initials: M
authors.lastname: Schmidt
authors.forename: John
authors.initials: J
authors.lastname: Hanna
authors.forename: Suzanne
authors.initials: S
authors.lastname: Elsasser
authors.forename: Daniel
authors.initials: D
authors.lastname: Finley
mesh_terms: D004789:Enzyme Activation; D004795:Enzyme Stability; D009097:Multienzyme Complexes / Q000737:chemistry / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000737:chemistry / Q000378:metabolism*; D011487:Protein Conformation; D013379:Substrate Specificity; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism; D014452:Ubiquitins / Q000378:metabolism
chemical_list: D009097:Multienzyme Complexes; D014452:Ubiquitins; D044767:Ubiquitin-Protein Ligases; D010447:Peptide Hydrolases; D046988:Proteasome Endopeptidase Complex