title: The proteasome 11S regulator subunit REG alpha (PA28 alpha) is a heptamer.
abstract: Activity of the 20S proteasome, which performs much of the cytosolic and nuclear proteolysis in eukaryotic cells, is controlled by regulatory complexes that bind to one or both ends of the cylindrical proteasome. One of these complexes, the 11S regulator (REG), is a complex of 28 kDa subunits that is thought to activate proteasomes toward the production of antigenic peptides. REG, purified from red blood cells, is a complex of REG alpha and REG beta subunits. We have crystallized recombinant REG alpha (rREG alpha) and collected diffraction data to 3.0 A resolution. The self-rotation function indicates that rREG alpha forms a heptameric ring in the crystal. Equilibrium sedimentation demonstrates that rREG alpha is a heptamer in solution also.
authors.affiliation: Biochemistry Department, University of Utah, Salt Lake City 84132, USA.
authors.forename: S C
authors.initials: SC
authors.lastname: Johnston
authors.forename: F G
authors.initials: FG
authors.lastname: Whitby
authors.forename: C
authors.initials: C
authors.lastname: Realini
authors.forename: M
authors.initials: M
authors.lastname: Rechsteiner
authors.forename: C P
authors.initials: CP
authors.lastname: Hill
mesh_terms: D001798:Blood Proteins / Q000737:chemistry*; D002500:Centrifugation, Isopycnic; D018360:Crystallography, X-Ray; D003546:Cysteine Endopeptidases; D004789:Enzyme Activation; D006801:Humans; D008958:Models, Molecular; D009097:Multienzyme Complexes; D046988:Proteasome Endopeptidase Complex; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry*
chemical_list: D001798:Blood Proteins; D009097:Multienzyme Complexes; D011506:Proteins; C088683:multicatalytic protease activator; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex