Studying lipid/protein interactions: From selfassembled model membranes to native nanodiscs

Model membrane systems of lipids with embedded peptides or proteins serve as useful tools to study lipid/protein interactions. I will discuss several examples of such studies. In one example, designed peptides mimicking transmembrane segments of membrane proteins were incorporated into lipid bilayers, allowing systematic variation of both lipid and peptide parameters. These studies showed in particular how a mismatch between bilayer thickness and hydrophobic length of the peptides may influence protein/lipid interactions. Another example involves the use of the amphipathic polymer styrene-maleic acid (SMA). This polymer has the remarkable ability to solubilize membranes in the form of nanodiscs, allowing detergent-free isolation of membrane proteins and characterization in their native environment. Based on model membrane studies, new applications of the SMA technology are being developed that offer intriguing possibilities for further studies of lipid/protein interactions.