Table 1.
Cryo-EM data collection, image processing, and model refinement statistics
| HCN4holo | HCN4apo/LC | HCN4apo/AM | |
| Data collection and image processing | |||
| Microscope | Titan Krios | Titan Krios | TALOS Arctica |
| Voltage (kV) | 300 | 300 | 200 |
| Camera | K2 Summit | K2 Summit | Falcon 3EC |
| Magnification | 29,000 | 29,000 | 120,000 |
| Total electron dose (e-/Å2) | 67.88 | 71.85 | 40.0 |
| Defocus range (μm) | −1 to −1.8 | −1.1 to −2 | −0.5 to −2.0 |
| Pixel size (Å) | 0.84 | 0.834 | 0.889 |
| Micrographs (no.) | 4,478 | 4,465 | 1,571 |
| Symmetry imposed | C4 | C4 | C4 |
| Initial particle images (no.) | 2,006,780 | 914,005 and 1,039,436 | 100,130 |
| Final particle images (no.) | 54,828 | 51,758 | 11,406 |
| Resolution (Å) (fourier shell correlation threshold) | 3.2 (0.143) | 3.2 (0.143) | 3.6 (0.143) |
| Sharpening B-factor (Å2) | −77.8 | −80.3 | −52 |
| EMDB code | EMD-12513 | EMD-12512 | EMD-12466 |
| Model refinement | |||
| Nonhydrogen atoms | 16,588 | 16,128 | 15,436 |
| Protein residues | 2,004 | 1,960 | 1,876 |
| cAMP molecules | 4 | – | – |
| N-acetyl-d-glucosamine molecules | – | 4 | – |
| Root-mean-square deviations (RMSDs) | |||
| Bond lengths (Å) | 0.008 | 0.008 | 0.010 |
| Bond angles (°) | 0.960 | 0.917 | 1.158 |
| Ramachandran plot | |||
| Favored (%) | 97.19 | 92.32 | 93.98 |
| Allowed (%) | 2.81 | 7.68 | 6.02 |
| Disallowed (%) | 0.00 | 0.00 | 0.00 |
| Validation | |||
| Molprobity score | 1.52 | 2.29 | 2.09 |
| Clashscore | 6.75 | 16.35 | 15.25 |
| Poor rotamers (%) | 0.22 | 1.35 | 0.88 |
| EM-Ringer Score | 3.75 | 2.64 | 1.55 |
| Map-model correlation | 0.84 | 0.82 | 0.80 |
| PDB code | 7NP4 | 7NP3 | 7NMN |