Chapter 1 Model membrane systems

Abstract

Summary The complexity of most biological membranes makes it extremely difficult to define the properties and roles of individual components in the native structure. For this reason simpler membrane models have been developed. These may comprise either lipid alone or both lipid and protein and ideally they should resemble the biological membrane as closely as possible. Lipid model membranes include vesicular systems such as large multilamellar vesicles, small, large, and giant unilamellar vesicles, as well as planar bilayers and monolayers. Of these systems large unilamellar vesicles often represent the most appropriate membrane model. This is also the case with reconstituted protein-lipid systems where, in addition, the protein should preferably have a defined transmembrane orientation. Using such model systems, it is possible to define the roles of particular lipid species and to identify and characterize individual membrane enzymes. In addition, both lipid-protein and protein-protein interactions can be studied. As our basic understanding of membrane structure and function improves, the versatility of the model-building approach will permit the development of increasingly more sophisticated systems. These in turn should allow us a deeper insight into the complexities of cell biology.