Two-dimensional crystallogenesis of transmembrane proteins

Two-dimensional crystallogenesis is a crucial step in the long road that le ads to the determination of macromolecules structure via electron crystallo graphy. The necessity of having large and highly ordered samples can hold b ack the resolution of structural works for a long time, and this, despite i mprovements made in electron microscopes or image processing. Today, findin g good conditions for growing two-dimensional crystals still rely on either "biocrystallo-cooks" or on lucky ones. The present review presents the hel d by first describing the different crystals that one can encounter and the different crystallisation methods used. Then, the effects: of different co mponents (such as protein, lipids, detergent, buffer, and temperature) and the different methods (dialysis, hydrophobic adsorption) are discussed. Thi s discussion is punctuated by correspondences made to the world of three-di mensional crystallogenesis. Finally, a guide for setting up 2D crystallogen esis experiments, built on the discussion mentioned before, is proposed to the reader. More than giving recipes, this review is meant to open up the d iscussions in this field. (C) 2001 Elsevier Science Ltd. All rights reserve d.