title: Structure and properties of the 26S protease complex from chick skeletal muscle.
abstract: The 26S protease complex was purified from chick skeletal muscle and shown to consist of unusually heterogeneous 21-140 kDa polypeptides, including the 21-32 kDa subunits of the 20S proteasome. Electron microscopic analysis revealed that the 26S complex may have a symmetric morphology with two large rectangular terminal domains attached to a thinner central 20S proteasome domain. The 26S complex was capable of degrading the peptide substrates of the 20S proteasome, including Suc-LLVY-AMC, N-Cbz-LLE-NA and N-Cbz-ARR-MNA. The two enzyme complexes showed similar sensitivities to various site-specific protease inhibitors, although their sensitivities to SDS were differed from each other. Immunoprecipitation with anti-26S complex antibody reduced peptide hydrolysis by the 20S proteasome. Similarly, anti-20S proteasome antibody inhibited peptide hydrolysis by the 26S complex. These results demonstrate that the 26S protease complex contains the 20S proteasome as a functional and structural component.
authors.affiliation: Department of Molecular Biology, College of Natural Sciences, Seoul National University, Korea.
authors.forename: D H
authors.initials: DH
authors.lastname: Lee
authors.forename: S S
authors.initials: SS
authors.lastname: Kim
authors.forename: K I
authors.initials: KI
authors.lastname: Kim
authors.forename: J Y
authors.initials: JY
authors.lastname: Ahn
authors.forename: K S
authors.initials: KS
authors.lastname: Shim
authors.forename: M
authors.initials: M
authors.lastname: Nishigai
authors.forename: A
authors.initials: A
authors.lastname: Ikai
authors.forename: T
authors.initials: T
authors.lastname: Tamura
authors.forename: K
authors.initials: K
authors.lastname: Tanaka
authors.forename: A
authors.initials: A
authors.lastname: Ichihara
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002645:Chickens; D003546:Cysteine Endopeptidases / Q000737:chemistry* / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases / Q000737:chemistry* / Q000378:metabolism; D006868:Hydrolysis; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000737:chemistry* / Q000378:metabolism; D009132:Muscles / Q000201:enzymology*; D010455:Peptides / Q000378:metabolism; D011480:Protease Inhibitors / Q000494:pharmacology; D046988:Proteasome Endopeptidase Complex
chemical_list: D009097:Multienzyme Complexes; D010455:Peptides; D011480:Protease Inhibitors; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex