Revival of electron crystallography.

Since the structure determination of bacteriorhodopsin in 1990, much progress has been made in the further development and use of electron crystallography. In this review, we provide a concise overview of the new developments in electron crystallography concerning 2D crystallization, data collection and data processing. Based on electron crystallographic work on bacteriorhodopsin, the acetylcholine receptor and aquaporins, we highlight the unique advantages and future perspectives of electron crystallography for the structural study of membrane proteins. These advantages include the visualization of membrane proteins in their native environment without detergent-induced artifacts, the trapping of different states in a reaction pathway by time-resolved experiments, the study of non-specific protein-lipid interactions and the characterization of the charge state of individual residues in membrane proteins.