Analysis of membrane protein composition by gel electrophoresis

Electrophoretic separation of proteins in gels is a universally popular technique whose application is not, of course, restricted to membrane proteins. Nevertheless, the need in membrane protein research for techniques for the separation and analysis of complex mixtures of hydrophobic proteins has perhaps provided a major impetus for the development of improved electrophoretic methods over the last decade, particularly the separation of sodium dodecyl sulphate (SDS)—protein complexes on polyacrylamide gels. The latter technique, and the complementary use of isoelectric focusing methods (Chapter 2), are the basis of many aspects of membrane protein research. In view of this importance, I make no apology that this chapter describes electrophoretic methods which can equally be applied to soluble proteins. However, I have concentrated on those methods which have proven to be most useful for membrane proteins and highlighted particular problems which may be encountered in membrane research.