The grab-and-drop protocol: a novel strategy for membrane protein isolation and reconstitution from single cellsIn memory of Mark Seller

We present a rapid and robust technique for the sampling of membrane-associated proteins from the surface of a single, live cell and their subsequent deposition onto a solid-supported lipid bilayer. As a proof of principle, this method has been used to extract green fluorescent protein (EGFP) labelled K-ras proteins located at the inner leaflet of the plasma membrane of colon carcinoma cells and to transfer them to an S-layer supported lipid bilayer system. The technique is non-destructive, meaning that both the cell and proteins are intact after the sampling operation, offering the potential for repeated measurements of the same cell of interest. This system provides the ideal tool for the investigation of cellular heterogeneity, as well as a platform for the investigation of rare cell types such as circulating tumour cells. Samples of cell membrane were non-destructively removed from individual, live cells using optically trapped beads, and deposited into a supported lipid bilayer mounted on an S-layer protein-coated substrate.