Fig. 3: The inner vestibule and loop^CT in the inward-facing conformation.

a The C-terminal loop extending from helix IH5 into the TMD helix bunding. The monomeric hAE2^acidic-KNO3 was shown as cartoon model and colored in blue, except for the loop^CT, colored in yellow. b The inner vestibule filled with the loop^CT. The monomeric hAE2^acidic-KNO3 was shown as transparent surface model, while the inner vestibule was determined with Hollow and shown as the solvent-accessible electrostatic surface–potential maps. The loop^CT was shown as cartoon model colored in yellow and stick model colored by elements. The residue R1060 at the dome part of the inner vestibule was also shown as stick model and colored by elements. The cell membrane region was shown as gray block in (a) and (b). c The interactions between the loop^CT and the inner vestibule. The loop^CT was shown as cartoon model colored in yellow and stick model colored by elements (gray-blue-red), with the residues from the surface of the inner vestibule interacting with the loop^CT were shown as stick model colored by elements (cyan-blue-red).