Fig. 1: Cryo-EM structures of the midnolin-26S proteasome complex in substrate-processing states.
From: Structural dynamics of the midnolin-proteasome during ubiquitin-independent substrate turnover
a Top: Schematic representation of full-length (FL) midnolin, highlighting its domains: ubiquitin-like (Ubl), nuclear localization sequence (NLS), intrinsically disordered region 1 (IDR1), and the C-terminal α-helix (αHelix-C). Bottom: A representative cryo-EM map of the midnolin-26S proteasome in a processing state (MIDN-PSRPT1), showing the midnolin αHelix-C (magenta) interacting with the RPN1(PSMD2) of the 19S regulatory particle. MIDN, short for midnolin throughout the figures. b Local refinement of RPN1 (pink) highlights its interaction with the midnolin αHelix-C (magenta). c Atomic model of midnolin αHelix-C and corresponding Cryo-EM map. d A low-pass filtered map (15 Å) shows midnolin/substrate density (red) at the N-ring entrance of 26S proteasome. e Cryo-EM map of the midnolin/substrate density in the central channel, reaching through the N-ring, the ATPase ring, and into the degradation chamber of the 20S core particle. Density maps in a, b, e were post-processed with EMReady for optimal visualization.
