Sequential treatment by phosphotungstic acid and uranyl acetate enhances the adherence of lipid membranes and membrane proteins to hydrophobic EM grids.

A simple procedure for screening by electron microscopic observations of conditions for the reconstitution of membrane proteins into lipid bilayers is described. This procedure consists of a 5-10 s treatment of electron microscopic grids, to which the sample has already been applied, with 1% phosphotungstic acid before proceeding with final staining in uranyl acetate. The method substantially enhances the adherence of lipid membranes and membrane protein particles to hydrophobic collodion/carbon grids.