Testing Parameters for Two-Dimensional Crystallization and Electron Crystallography on Eukaryotic Membrane Proteins with Liposomes as Controls

Abstract

Membrane proteins comprise the majority of known and potential drug targets, yet have been immensely difficult to analyze at the structural level due to their location in the membrane bilayer. Removal from the membrane necessitates replacement of the phospholipid bilayer by detergents in order to maintain protein solubility. However, the absence of lipids and the presence of detergents can render non-physiological conformational changes of the membrane protein (Tate, 2006). Electron crystallography is an important method for studying membrane proteins that usually takes advantage of reconstituting the protein in a phospholipid bilayer and removal of the detergent. Richard Henderson and Nigel Unwin used this technique to elucidate the three-dimensional (3D) arrangement of the transmembrane α-helices of bacteriorhodopsin, which was the first 3D structural information on a membrane protein (Henderson and Unwin, 1975).