Probing Interphase Partitioning and Dynamics within Phase Separated Supported Biomembranes

Proteolipobead systems (PLBs) have been used to directly visualize and quantify interphase partitioning and dynamics in micropshere supported biomembranes.  We have constructed PLBs using a lipid compostions that give phase separation and loaded alpha-helical peptides to study peptide phase partioning and diffusivity. Confocal and superresolution fluorescence microscopy has been used to probe biomembrane structures and cholesterol-rich nano- and microdomain formation.  Fluorescence-based PLB flow cytometry is used to probe the large PLB populations and evaluate biomembrane quality and surface coverages. Control of lipid phase separation and composition in proteolipobead systems forms the basis of a new in vitro methodology to investigate the influence of cholesterol-rich membrane microdomains on the efficiency, specificity, and inhibition of protease and lipase enzymes that are embedded in biomembranes such as the Alzheimers and cancer drug target gamma-secretase.