Titan Krios Cryo-Electron Microscopy Data Collection Parameters

The grids were loaded onto the Titan Krios cryo-electron microscope (Thermo Fisher) set at 300 kV, with a 50 μm objective aperture, 6 spot size, 165,000× magnification (calibrated sampling of 0.85 Å per physical pixel), and a K2 direct electron detector with BioQuantum energy filter set to 20 eV (Gatan). Data was automatically collected with the EPU2.9.1 software (Thermo Fisher), using the K2 detector in counting mode at a recording rate of 5 raw frames per second for a total exposure time of 6 seconds. Each movie stack consisted of 30 frames, resulting in a total dose of 63 e-/Å2.