Illustration of a close-up of a DNA (deoxyribonucleic acid) origami signpost molecule. This is a manmade nanostructure used to tag and identify proteins. The post section of the molecule (not seen) binds to a specific protein target in a sample of cells or viruses. The imaging technique electron cryotomography (cryo-ET) can then be used to find the sign portion of the molecule, which has a distinctive signal, and locate the protein of interest.