The scanning transmission electron microscope precision and reproducibility of mass measurements are comparable with those of the analytical ultracentrifuge, the possibility of determining the mass not only of entire supramolecular assemblies but also of their distinct components has opened exciting new avenues which have occasionally been entered but are not yet fully explored. Includes: Principle and application (The GroEL:GroES complex).

Protocol: Imaging and Measuring Biomolecules & Their Assemblies by Scanning Transmission Electron Microscopy