Genetically encoded multimeric particles (GEMs) can be used to tag and identify proteins inside the cytoplasm.93Left: overlay of on-lamella cryo-FM image and cryo-TEM overview image of a human cell with GEM-labeled lipid droplet protein seipin (GEM2 fluorescence, magenta; seipin-GFP, green). Inset shows overview of the lamella with overlaid cryo-FM signals. Middle: virtual cryo-ET slice of the same area; the white box highlights the connection between the endoplasmic reticulum and the lipid droplet where seipin is present (magnified in inset). Right: segmentation of the volume shown in middle image, with GEMs (magenta), a lipid droplet (yellow), ER (blue), mitochondria (green), and ribosomes (gray). Scale bars: 200 nm (main images), 5 μm (first inset), 20 nm (second inset).
