Fig. 3: Single-particle cryo-EM structure of PA26PANc-αWTββαK66A complex.
From: Allosteric coupling between α-rings of the 20S proteasome
a Cryo-EM reconstruction of PA26PANc-αWTββαK66A at a resolution of 2.9 Å. Samples were prepared without substrate LFP peptide substrate present. b Proximal α-ring of the 20S CP. c Ribbon diagram of proximal α-ring (green) overlayed with that of the α-ring in closed conformation without bound activator (purple). Note that the two do not overlap, indicating rotation induced by activator binding. d Ribbon diagram of α-subunits from proximal α-rings. The N-terminus of a-subunit within the dashed box points upwards in an open gate conformation. e Ribbon diagrams of an α-subunit from the proximal α-ring and its interacting β-subunit (green) overlaid with the ribbon diagram of α/β-subunits from a 20S CP without activator bound (purple). Note that the β-subunit is perfectly aligned between the two, but α-subunit is rotated. f The distal α-ring of the 20S CP. g Ribbon diagram of distal α-ring (green) overlayed with that of the α-ring in closed conformation without bound activator (purple). Note that the two overlap nicely. h Ribbon diagram of α-subunits from distal α-rings, where the N-terminus of a-subunit within the dashed box points upwards in an open gate conformation.
