title: Reconstitution of hybrid proteasomes from purified PA700-20 S complexes and PA28alphabeta activator: ultrastructure and peptidase activities.
abstract: The activity of the proteasome, the major non-lysosomal proteinase in eukaryotes, is stimulated by two activator complexes, PA700 and PA28. PA700-20 S-PA700 proteasome complexes, generally designated as 26 S proteasomes, degrade proteins, whereas complexes of the type PA28-20 S-PA28 degrade only peptides. We report, for the first time, the in vitro reconstitution of previously identified hybrid proteasomes (PA700-20 S-PA28) from purified PA700-20 S proteasome complexes and PA28 activator. In electron micrographs, the hybrid appears as a corkscrew-shaped particle with a PA700 and a PA28 activator each bound to a terminal alpha-disk of the 20 S core proteasome. The multiple peptidase activities of hybrid proteasomes are not different from those of PA28-20 S-PA28 or PA700-20 S-PA700 complexes.
authors.affiliation: Department of Clinical Biochemistry, Deutsches Diabetes-Forschungsinstitut, Düsseldorf, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Kopp
authors.forename: B
authors.initials: B
authors.lastname: Dahlmann
authors.forename: L
authors.initials: L
authors.lastname: Kuehn
mesh_terms: D000595:Amino Acid Sequence; D003546:Cysteine Endopeptidases / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism / Q000648:ultrastructure*; D006801:Humans; D046911:Macromolecular Substances; D008854:Microscopy, Electron; D009097:Multienzyme Complexes / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism / Q000648:ultrastructure*; D009124:Muscle Proteins; D046988:Proteasome Endopeptidase Complex; D020836:Protein Structure, Quaternary; D021122:Protein Subunits; D011506:Proteins / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism* / Q000648:ultrastructure; D013379:Substrate Specificity
chemical_list: D046911:Macromolecular Substances; D009097:Multienzyme Complexes; D009124:Muscle Proteins; C085834:PA700 proteasome activator; C085047:PSME1 protein, human; D021122:Protein Subunits; D011506:Proteins; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex