Imaging of G protein-coupled receptors in solid-supported planar lipid membranes

This contribution summarizes first some of our efforts in imaging G-protein-coupled receptor (GPCR) functional inserted into planar tethered lipid bilayer membranes (tBLMs) as a novel platform for biophysical studies. The authors introduced recently a novel approach for the functional incorporation of membrane proteins, i.e., by their cell-free expression and in vitro reconstitution in the presence of tBLMs. By the combination of the corresponding coding DNA with the protein synthesis machinery of a cell-extract (in vitro transcription and translation), the authors observe spontaneous and vectorial insertions of an interesting example of the GPCR family into a tethered bimolecular lipid membrane: the olfactory receptor OR5. After synthesis, imaging of the surface area is performed and the resulting signals are analyzed in order to resolve quantity and lateral mobilities. Ligand-independent aggregation behavior of the GPCRs and quantitative analysis of the fluorescent signals are presented in this work.