ABSTRACT
The translational diffusion of membrane proteins was one of the key observations used to establish the current fluid-mosaic model of cell membranes (Singer and Nicolson, 1972). Measurements of translational diffusion of membrane proteins are interesting in two respects. First, such measurements address some physical problems about diffusion in the protein-rich, two-dimensional fluids that constitute cell membranes, in particular, problems about the forces retarding diffusion. Second, studies of translational dynamics of membrane proteins address questions of membrane organization and function. Measurements of translational diffusion are used to analyze the fine structure of cell membrane organization and to detect associations among membrane proteins and between these proteins and the cell cytoplasm. Such associations are biologically important in forming functioning receptors and in signaling by such receptors.
