Research Paper Volume 16, Issue 6 pp 5501—5525

Figure 2. Cryo-EM structure of human EMC. (A) The cryo-EM density map and ribbon diagram of the human EMC complex, color-coded to highlight the subunit arrangement. (B) A close-up view of the EMC3 transmembrane module. The L-shape Segment^188–210 of EMC3 are highlighted in magenta, and the rest of the EMC3 colored in plum. (C) A close-up view of the transmembrane module showing the two transmembrane cavities in the EMC. The internal cavities, determined by program HOLLOW, are shown as surface representation and the EMC in cylinder model. The extended loop of the L-shape Segment^188–210, which separates the hydrophilic vestibule from the hydrophobic cavity, is highlighted by a dashed box. (D) The front view of the horseshoe-shaped hydrophilic vestibule. The L-shaped EMC3 segment and the nine-TMH bundle of EMC3-EMC4-EMC6 are shown. The horizontal helix of the L-shaped EMC3 segment that forms the base of the hydrophilic vestibule, is highlighted by a dashed box. (E) The front view of the EMC transmembrane region in electrostatic surface potential (positive: blue; negative: red). The entrance of the hydrophilic vestibule is defined by a dashed circular loop.