2010 Volume 45 Issue 4 Pages 243-249
Cryo-electron microscopy (cryo-EM) is now being widely used to analyze biological macromolecular structures because it can be applied to various forms of samples, although attainable resolution is generally not so high. Helical reconstruction and single particle analysis of highly-symmetrical huge particles have now reached to a resolution better than 4Å, and allowed to visualize densities of amino-acid side chains and build the atomic models directly from the density maps. In this article, I will introduce examples of high-resolution cryo-EM structures such as the bacterial flagellar filament and a spherical virus, and review imaging conditions towards higher resolutions. The article also covers new digital imaging devices and energy filtering.