Extended Data Table 1:
Cryo-EM data collection, refinement and validation statistics.
| pH8-PAC | pH4-PAC | |
|---|---|---|
| Data collection and processing | ||
| Magnification | 130,000 | 130,000 |
| Voltage (kV) | 300 | 300 |
| Electron exposure (e−/Å2) | 49.6 | 49.6 |
| Defocus range (jun) | −1.2 to−1.9 | −1.2 to−1.9 |
| Pixel size (Å) | 1.026 | 1.026 |
| Symmetry imposed | C3 | C3 |
| Initial particle images (no.) | 4,515,826 | 6,647,983 |
| Final particle images (no.) | 323,766 | 48,551 |
| Map resolution (Å) | 3.60 | 3.73 |
| FSC threshold | 0.143 | 0.143 |
| Map resolution range (Å) | 3.60–246.2 | 3.73–246.2 |
| Refinement | ||
| Initial model used (PDB code) | De novo | De novo |
| Model resolution (Å) | ||
| FSC threshold | 3.87 | 3.93 |
| Map sharpening B factor (Å2) | −180.05 | −148.66 |
| Model composition | ||
| Non-hydrogen atoms | 6432 | 6573 |
| Protein residues | 834 | 861 |
| Ligands | 0 | 0 |
| R.m.s. deviations | ||
| Bond lengths (Å) | 0.004 | 0.004 |
| Bond angles (°) | 0.627 | 0.617 |
| Validation | ||
| MolProbity score | 1.87 | 2.07 |
| Clashscore | 11.12 | 16.75 |
| Poor rotamers (%) | 0.00 | 0.00 |
| Ramachandran plot | ||
| Favored (%) | 95.65 | 95.09 |
| Allowed (%) | 4.35 | 4.91 |
| Disallowed (%) | 0.00 | 0.00 |