Investigating membrane protein function and oligomerization with Nanodiscs.
The nanodisc is a model membrane system useful to study membrane proteins. The nanodisc defines a small patch of lipid bilayer (~ 10-12 nm in diameter) stabilized by two amphipathic proteins, termed membrane scaffold proteins (MSPs). The two MSPs wrap around the hydrophobic core of the lipids, effectively creating a water-soluble disc of membrane (Figure 1). The nanodisc is a particularly attractive option for studying membrane proteins, especially in the context of ligand-receptor interactions. Analyze of membrane proteins in nanodiscs have significant advantages over liposome because the particles are small, homogeneous and water-soluble. In addition, biochemical and biophysical methods normally reserved for soluble proteins can be applied, and from either side of the membrane. Various membrane transporters are being studied in the laboratory using the nanodiscs - the SecYEG protein-conducting channel, the MalFGK maltose transporter and the FhuA outer membrane porin responsible for iron uptake (Figures 2 to 4). We are also using nanodiscs in a proteomics approach to identify and analyze proteins bound at the surface of various type of cell membranes.
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