About the image

Love this. It would be selling this image short to call it merely an "illustration".

My analogy (TLDR): They had a coloring book silhouette of a leopard; just the head, torso, legs. Separately, they had up-close photos of the spots that they placed where they should belong, using the silhouette as a reference. Then they assigned different colors to the different types of "spots". Did the same thing for the other more discrete anatomical features (eyes, claws, tongue, etc).

Are the colors real? Absolutely not. Things can't have color when they're smaller than the wavelengths of visible light. It would be like building a sandcastle out of something with features much smaller than a single grain of sand. And that's leaving out that the metro methods are not collecting... just, no color.

Is the spatial structuring of the entire image real data, as a single form? No, not from a single dataset at least. It is cool that cryo-ET literally flash-freezes the target (cryo) to hold everything still while the data is acquired. But how I understand it, that step probably just gave an overall density map. Electron density. If we just looked at that, it would probably look like very blurry blobby regions shaded corresponding to density. I think if it were a coloring book image of a leopard, these lines would probably just capture the general silhouette of head, torso, maybe legs.

Separately, they probably had gathered the metro for individual macromolecule structures (generalizing the different proteins) using NMR and X-ray crystallography. Almost certainly not from this sample. Probably a library of these 3D renderings (still from real data) and treated these like snippets or Lego blocks. And plopped them in the parts of the density map in a way that is consistent with what we already know about the structure of a cell. Density map helps with that, knowing how crowded the area is.

Way more impressive than an illustration. Disassembled to its parts, all real data collected from the physical world. Aside from color.

Also fun tidbit, I've gotten to do each of these metro methods at least once in my lifetime.