Structure of ryRyR1 at a resolution of 17.5 Å. Two views are through the middle slice (top) of the reconstruction and at the level of sarcoplasmic extentions 22 Å below (bottom panels). The movement of the outer domains is associated with a visible change in membrane curvature as compared to the apo-structure. This movement is highlighted by red arrows in the right panels. Scale bar: 10 nm. 