Surfactosomes: a novel approach to the reconstitution and 2-D crystallisation of membrane proteins.

The formation of vesicle-like structures (termed surfactosomes) and lamellar sheets from solutions containing ammonium perfluoroocanoate (APFO) is illustrated using conventional and cryo-transmission electron microscopy. It is shown how this detergent can be used for the solubilisation, reconstitution and 2-D crystallisation of membrane proteins as demonstrated for the major protein of the membrane sector of the V-type H+-ATPase (16-kDa protein). Electron microscopical analysis of 2-D crystals of the 16-kDa protein (a=b=13.0+/-0.2nm with gamma = 90 degrees and p4 projection symmetry) revealed a unit cell comprising four dimeric complexes of the 16-kDa protein the significance of which is discussed.