Two‐dimensional crystallization of proteins on planar lipid films and structure determination by electron crystallography*

Electron crystallography constitutes a powerful new method for determining the structure of biological macromolecules. This method is best adapted to the study of ordered assemblies of macromolecules, and principally to two-dimensional (2-D) crystals of proteins. Obtaining protein 2-D crystals ordered at high resolution constitutes the major limiting step in the application of this approach. Considerable interest has been raised by the development of a rational method of 2-D crystallization based on the specific binding of proteins to planar lipid films. The applicability of this method is quasi-general in the case of soluble proteins. Its basic principles, together with examples taken from work in our group, are presented here.