Structure and Dynamics of Membrane Proteins and Membrane Associated Proteins with Native Bicelles from Eukaryotic Tissues.

ABSTRACT

In vitro studies of protein structure, function, and dynamics typically preclude the complex range of molecular interactions found in living tissues. In vivo studies elucidate these complex relationships, yet they are typically incompatible with the extensive and controlled biophysical experiments available in vitro. We present an alternative approach by extracting membranes from eukaryotic tissues to produce native bicelles to capture the rich and complex molecular environment of in vivo studies while retaining the advantages of in vitro experiments. Native bicelles derived from chicken egg or mouse cerebrum tissues contain a rich composition of phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), phosphatidylserine (PS), phosphatidylinositol (PI), phosphatidic acid (PA), lysolipids, cholesterol, ceramides (CM), and sphingomyelin (SM). The bicelles also contain source-specific lipids such as triacylglycerides (TAGs) and sulfatides from egg and brain tissues, respectively. With the influenza hemagglutinin fusion peptide (HAfp) and the C-terminal Src homology domain of lymphocyte-specific protein-tyrosine kinase (lck-cSH2), we show that membrane proteins and membrane associated proteins reconstituted in native bicelles produce high-resolution NMR data and probe native protein-lipid interactions.