Visualizing individual rhodopsin (a G protein-coupled receptor) molecules in native disk and reconstituted membranes via atomic force microscopy

Individual rhodopsin molecules have been resolved with atomic force microscopy as both monomers and various oligomeric organizations that are sensitively dependent upon the physical state of membranes and environmental conditions. In intact native disk membranes, rhodopsin molecules are observed as randomly dispersed monomers and small oligomers. In reconstituted rhodopsin-DPPC (dipaimitoylphosphatidylcholine, di16:0-PC) membranes, phase separation of lipid and rhodopsin results in paracrystalline arrays of rhodopsin molecules. Since the coupling of rhodopsin and G proteins is an essential step in visual transduction, the results from this study could provide further insight into the structural relationship of rhodopsin to its function in vision and may have applications in nanotechnology.