Supported Cell Membrane Sheets to Monitor Protein Assembly.

Studying protein-protein and protein-lipid interactions in their native environment is highly desirable, yet, the heterogeneity and complexity of cellular systems limits the repertoire of experimental methods available. In cells, interactions are often taking place in confined microenvironments where factors such as avidity, hindered diffusion, reduced dimensionality, crowding etc. strongly influence the binding kinetics and therefore it can be problematic to equate binding affinities obtained by bulk in-solution methods (e.g., Fluorescence Polarization, Isothermal titration calorimetry, Microscale thermophoresis) with those occurring in real cellular environments. The Supported Cell Membrane Sheet method presented here, addresses these issues by allowing access to the inner leaflet of the apical plasma membrane. The method is a highly versatile, near-native platform for both qualitative and quantitative studies of protein-protein and protein-lipid interactions occurring directly in or on the plasma membrane.