R2 2 finder em grids

The RAW 264.7 cells were plated on the gold R2/2 Quantifoil finder EM grids (Quantifoil Micro Tools GmbH), which were pre‐coated with 100 µg/ml collagen IV (BD Biosciences) and disinfected under UV light for 2 h. The cells were cultured on the grids overnight and then cultured in the glucose‐depleted medium for 2 h. Next, the cells incubated with the anti‐GARS1 antibody were imaged using a confocal fluorescence microscope. Further, 4 µl of PBS was applied to the cell culture on the gold EM grids for further preparative steps. Rapid verification and cryo‐EM observations were conducted as described above. The fluorescence‐labelled regions were manually identified under EM projection images captured under a series of magnifications (140× to 21,000×) to correlate with confocal fluorescence microscopy images. The low dose (approximately 20 e⁻/Ų) projection images of the identified region were recorded at under‐focus values ranging from 5 to 8 µm.