Extended Data Fig. 4: Cryo-EM density of the initiation and elongation complexes.
From: Structural insights into Ubr1-mediated N-degron polyubiquitination
a, Individual domains of Ubr1 in the initiation complex. b, Ubc2 and Ub in the initiation complex. c, Ubc2, donor Ub and acceptor Ub in the elongation complex. Maps in a and b were sharpened using a B factor of −96.5 Å2 and contoured at a level of 0.030. Maps in c were sharpened using a B factor of −96.7 Å2 and contoured at a level of 0.022. d, Degron recognition site of the initiation complex. e, Active site of the initiation complex. f, Three-domain junction of the initiation complex. g, Active site of the elongation complex. h, Acceptor Ub and Ubr1 binding interface in the elongation complex. i, Acceptor Ub and Ubc2 binding interface in the elongation complex. Dotted circles in d and e mark the unmodelled densities corresponding to the Degron peptide which are only visible at the lower contour levels. Atomic models could not be reliably built into the densities.
