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. 2024 Sep 2;12:RP90851. doi: 10.7554/eLife.90851

Figure 2. Electron crystallography provides structures of aquaporin-0 (AQP0) in sphingomyelin/ cholesterol bilayers at 2.5 Å resolution.

(A) Electron diffraction pattern of an untilted AQP0 two-dimensional (2D) crystal reconstituted at a sphingomyelin:cholesterol ratio of 2:1, showing reflections to ~2 Å resolution. Scale bar indicates (10 Å)–1. (B) Density map at 2.5 Å resolution used to build the AQP02SM:1Chol structure. A region of the water-conducting pathway close to the NPA (asparagine-proline-alanine), the AQP signature motif, is shown. The 2Fo-Fc map contoured at 1.5σ is shown as gray mesh, the AQP0 model is shown in yellow with oxygen atoms in red and nitrogen atoms in blue. The red sphere represents a water molecule. (C) A diffraction pattern of an untilted AQP0 2D crystal reconstituted at a sphingomyelin:cholesterol ratio of 1:2, showing reflections to better than 1.6 Å resolution. Scale bar indicates (10 Å)–1. (D) Density map at 2.5 Å resolution used to build the AQP01SM:2Chol structure. The same region as in (B) is shown with the same color code. See also Figure 2—figure supplement 1.

Figure 2.

Figure 2—figure supplement 1. Electron diffraction patterns of two-dimensional (2D) crystals reconstituted with sphingomyelin/cholesterol mixtures tilted to 60°.

Figure 2—figure supplement 1.

(A) Background-subtracted electron diffraction pattern of a 60° tilted aquaporin-0 (AQP0) 2D crystal reconstituted at a molar sphingomyelin:cholesterol ratio of 2:1. The boxed reflection corresponds to a resolution of 2.52 Å resolution. (B) Background-subtracted electron diffraction pattern of a 60° tilted AQP0 2D crystal reconstituted at a molar sphingomyelin:cholesterol ratio of 1:2. The boxed reflection corresponds to a resolution of 2.46 Å resolution. Scale bars indicate (10 Å)–1.