Extended Data Fig. 8: Features of the Rho-4TMD map and model.

a, Flowchart depicting the classification scheme and analysis of cryo-EM micrographs of the Rho-4TMD RNC sample. The classes denoted as “TRAP complex” appear to only contain the core translocon comprised of the Sec61 and TRAP complexes, evidently in somewhat different conformations, as characterised previously in cryo-EM and cryo-electron tomography work^26,61,62,63. These were not pursued further. b, Fourier shell correlation (FSC) curve for the Rho-4TMD map illustrating an overall resolution of 3.88 Å by the gold-standard method⁶⁴. c, Two views of the Rho-4TMD reference map coloured by local resolution. Key structural elements, including the density assigned to TMD3 of the substrate, are indicated. d, Space-filling models showing the multipass translocon’s highly conserved interior surface that faces the lipid-filled cavity (left) and poorly conserved exterior surface that faces the surrounding membrane (right). The models are coloured successively (from top to bottom) by protein, hydrophobicity, charge and conservation (calculated by ConSurf⁶⁵). The conserved amphiphilic substrate-binding domain of the PAT complex, the conserved positively-charged hydrophilic vestibule of the GEL complex, and the conserved Sec61-docking site on the BOS complex are each indicated.