Fig. 1: Cryo-EM structure and atomic model of full-length p62 filaments.

a p62 domain plot including main interaction sites: the N-terminal PB1 domain responsible for self-polymerization, followed by the zinc finger ZZ domain, a long region of predicted disorder including the LC3-interacting region (LIR) motif and the C-terminal UBA domain recognizing ubiquitinylated cargo. UBA domains of neighboring p62 proteins can interact with each other through the bound poly-ubiquitin. b Representative cryo-micrograph (out of 4038) with long and flexible p62 filaments. c 2D classes showing well-defined densities of the filamentous scaffold in addition to blur, including apparent variation in pitch, with higher helical pitch classes (red frame) and lower helical pitch classes (yellow frame). d Three-dimensional density of p62 colored according to local resolution values showing PB1 domains arranged in a left-handed double helical architecture. The map rendered at three different thresholds (left, center, right) shows that the PB1 domain is well-resolved (~4.5 Å resolution), the ZZ domain appears as a featureless blob at ~6.5 Å resolution, and the remaining C-terminal domains are not well resolved. e Left: The atomic model of the PB1 domain fits well into the well-defined PB1 density at a higher threshold. Right: The atomic model of the ZZ domain of p62 fits in the featureless blobs seen at a lower threshold. f The atomic model of the helical p62 filament with highlighted PB1 (cyan) and ZZ (green) domains fitted into the filament density displayed at a low threshold. The experiment on the cryo-EM for structure determination was conducted once (N = 1), and 4038 micrographs were collected.