`Cryo-EM': electron cryomicroscopy, cryo electron microscopy or something else?

Abstract

Structural biology continues to benefit from an expanding toolkit, which is helping to gain unprecedented insight into the assembly and organization of multi-protein machineries, enzyme mechanisms and ligand/inhibitor binding. During the last ten years, cryoEM has become widely available and has provided a major boost to structure determination of membrane proteins and large multi-protein complexes. Many of the structures have now been made available at resolutions around 2 Å, where fundamental questions regarding enzyme mechanisms can be addressed. Over the years, the abbreviation cryoEM has been understood to stand for different things. We wish the wider community to engage and clarify the definition of cryoEM so that the expanding literature involving cryoEM is unified.

Keywords: cryo electron microscopy; cryoEM; electron cryomicroscopy; nomenclature; standardization.

Figure 1

(a) Growth of cryoEM structures during the last 10 years. In 2022 the number of deposited cryoEM structures approached over 4000 compared with around 9800 X-ray structures. cryoEM structures were mostly of membrane proteins and large complexes. (b) Resolution of cryoEM structures that are now available, nearly 200 structures are now known to ∼2.2 Å resolution.