Imaging of FRL-PSI was performed on a Titan Krios G2 transmission electron microscope (Thermo Fisher Scientific/FEI, Hillsboro, OR). Images were recorded on a K2 Summit direct electron detect camera (Gatan, Pleasanton, CA) in super-resolution mode. The defocus varied from −1 to −3 μm, and the nominal magnification was 47,600, corresponding to a super-resolution pixel size of 0.53 Å at the specimen level. The counting rate was adjusted to 7.166 e pixel−1 s−1. The total exposure time was 8 s, accumulating to a dose of 57.328 e Å−2. In total, 6593 micrograph images were collected. SerialEM automated data collection using the K2 Summit and Titan Krios GS resulted in 3692 LZW-compressed tiff movie files (43).