Lipid-Protein Interactions and Acetylcholine Receptor Function in Reconstituted Membranes

Abstract

The role of dynamic lipid-protein interactions in regulating the functional activity of membrane proteins has been extensively examined using a wide variety of biophysical techniques (1). The lipids in direct contact with membrane proteins are usually exchangeable with bulk lipids, although the two different types of lipid environments can be readily detected using electron spin resonance techniques (2–4). There is some selectivity in the apparent binding of lipids at the lipid-protein interface, and many membrane proteins are preferentially activated or inhibited by different classes of lipid. However, it has been difficult to establish clear links between lipid-protein interactions and direct effects of lipids on membrane protein function. In part, the problem reflects the comlexity of lipid compositions in native biological membranes and the inherent risks of examining relevant functional properties of membranes in reconstituted systems containing completely defined components. In addition, there may be specific requirements for some membrane proteins that cannot be generalized to predict the effects of lipids on other membrane proteins.