Figure 1. Overall structure of the KATP channel bound to ATP and GBC.
(A) Linear sequence diagram for the Kir6.2 and SUR1 polypeptides, with primary domains colored to match the panels below. Numbers indicate residue number at the beginning and end of each domain. (B) Cryo-EM density map of the KATP channel complex at 3.63 Å resolution, viewed from the side. Gray bars indicate approximate position of the bilayer. (C) View of map from extracellular side. (D). Structural model of the complex, with ligands ATP (green) and GBC (red) in boxes. (E) View of the model from the extracellular side.
Figure 1—figure supplement 1. Data collection and image processing workflow.
(A) Representative micrograph at 81,000x (1.72 Å/pixel; 0.86 Å/pixel super-resolution) after alignment with Motioncor2. A few KATP channel complexes of various orientation have been outlined. (B) Power spectrum calculated with Ctffind4, with information extending out to 3.6 Å. (C) Select 2D classes from the final round of classification. (D) Overview of the data processing workflow. Particle picking was performed automatically with DoGPicker as well as with manual inspection. All other image processing steps were performed in Relion-2 and Frealign.
Figure 1—figure supplement 2. Cryo-EM density map analysis.
(A) Euler angle distribution plot of all particles included in the calculation of the final map. (B) The EM density map with colored local resolution estimation using Bsoft. (C) Fourier shell coefficient (FSC) curves between two half-datasets calculated by Frealign. The refinement limit of 4.8 Å used in Frealign is indicated by the vertical dotted line. (D) FSC curves between the refined structure and the map calculated from the full dataset (FSC sum, orange), the half-map used in refinement (FSC work, grey), and the other half-map (FSC free, gold).