Fig. 1.

Initial negative-stain 3D reconstructions of cross-linked p97-Ufd1-Npl4 and Ufd1-Npl4 incubated with glutaraldehyde. (A) 3D reconstruction of p97-Ufd1-Npl4 shows additional density placed on top of the ring spanning the central pore of p97 and connected to the ring by two densities. (B) Side-view class averages displaying additional density on top of the p97 double ring structure. (C) Class averages (Top), reprojections (Middle), and raw particles (Bottom) of the Ufd1-Npl4 structure. (D) The 3D reconstruction of cross-linked Ufd1-Npl4. The model displays a bilobed shape of two densities of different sizes. (E) Fitting of the N-terminal domain of Ufd1 [PDB accession code: 1ZC1 (37)] shows an overall agreement in size and shape between the atomic coordinates and the smaller of the two lobes of the EM map. (Scale bars: 20 Å.) (See also Fig. S1.)