ABSTRACT
This chapter focuses on membrane proteins rather than membrane lipids, a few examples of the application of membrane-splitting analyses to amphipathic and hydrophobic molecules are given as an introduction. The freeze-fracture technique is routinely used as a morphological and cytochemical method. However, it can also be viewed as a physical fractionation or separation technique, analogous to differential centrifugation, chromatography, or gel electrophoresis. Techniques of planar cell and membrane freeze fracture have been developed to produce split membrane fractions in quantities suitable for direct chemical and physical analysis. Microscopic, spectroscopic, and fluorometric methods have been developed to quantify the amount of each split membrane leaflet produced. As with peripheral membrane proteins, the location of integral proteins relative to the plane of fracture is important in determining the effect of membrane splitting. However, the effects of membrane splitting on integral membrane proteins are less predictable than the effects on peripheral proteins.
