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Figure 3
Structural comparison of the type I and type II OF crystal structures of CmABCB1QTA. (a) Structure alignment of the two types of crystal structures. Black solid lines indicate the boundaries of the lipid bilayer. Black dashed lines indicate the middle of the lipid bilayer. Red solid lines and a red ellipse indicate regions enlarged in (b), (c), and (d). Ellipses with blue dashed lines in (a) and (b) indicate the cleft of the substrate exit. (b) Displacement of the TM helices at the outer leaflet region constituting the substrate exit. (c) The inner leaflet part of the TM helices exhibits little difference. (d) Nucleotide-binding sites of the two structures. The βDM molecule belongs to the type II structure and the Zn ion belongs to the type I structure. The blue mesh shows a 2Fo − Fc electron-density map of AMPPNP in the type I structure, contoured at the 1.5σ level.

IUCrJ
Volume 9| Part 1| January 2022| Pages 134-145
ISSN: 2052-2525
https://doi.org/10.1107/S2052252521011611