a, Structure of the EMC lumenal region shown in front side and bottom (lumenal) views. The interface area between the C-terminal loop of Emc4 and the NTD2 of Emc1 is outlined by a red rectangle. The dotted black area marks the NTD2 of Emc1, which is an eight-bladed β-propeller. b, Superposition of the NTD2 β-propeller of Emc1 with the structure of a fungus chaperone protein Sqt1 (PDB code 4ZN4). c, Enlarged view of the red-outlined region in a. d, Structure of the EMC cytosolic region in top (cytosolic) and front side views. Emc2 as the organizing centre is shown in cartoon, and the cytosolic domains of Emc3, Emc4 and Emc5 are shown as cylinders.