title: Structural analysis of the 26S proteasome by cryoelectron tomography.
abstract: The 26S proteasome is the key enzyme of intracellular protein degradation in eukaryotic cells. It is a multisubunit complex of 2.5 MDa confining the proteolytic action to an inner compartment with tightly controlled access. Structural studies of this intriguing molecular machine have been hampered by its intrinsic instability and its dynamics. Here we have used an unconventional approach to obtain a three-dimensional structure of the holocomplex uncompromised by preparation-induced alterations and unbiased by any starting model. We have performed a tomographic reconstruction, followed by averaging over approx. 150 individual reconstructions, of Drosophila 26S proteasomes suspended in a thin layer of amorphous ice.
authors.affiliation: Max-Planck-Institute of Biochemistry, Department of Structural Biology, Am Klopferspitz 18, D-82152 Martinsried, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Nickell
authors.forename: Oana
authors.initials: O
authors.lastname: Mihalache
authors.forename: Florian
authors.initials: F
authors.lastname: Beck
authors.forename: Reiner
authors.initials: R
authors.lastname: Hegerl
authors.forename: Andreas
authors.initials: A
authors.lastname: Korinek
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Baumeister
mesh_terms: D020285:Cryoelectron Microscopy / Q000379:methods*; D003461:Crystallography / Q000379:methods; D029721:Drosophila Proteins / Q000648:ultrastructure*; D046988:Proteasome Endopeptidase Complex / Q000648:ultrastructure*; D011487:Protein Conformation; D014054:Tomography / Q000379:methods*
chemical_list: D029721:Drosophila Proteins; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease