Detection and analysis of protein-protein interactions of organellar and prokaryotic proteomes by blue native and colorless native gel electrophoresis

Native gels enable the analysis of protein complexes on a proteome-wide scale in a single experiment. The protocols described in this unit are based on separation of protein complexes by blue native polyacrylamide electrophoresis (BN-PAGE), the most versatile native gel system, and the closely related milder colorless native PAGE (CN-PAGE). Both BN-PAGE and CN-PAGE are described on analytical to preparative scales. In addition, methods for subsequent analysis of protein complexes are given, including electroelution from native gels as well as denaturing and native two-dimensional PAGE. Finally, the removal of Coomassie dye from electroeluted proteins is detailed along with a discussion of fundamental considerations for the solubilization of membrane protein complexes from various biological samples, which are exemplified for mitochondria, chloroplasts (thylakoids), and cyanobacteria.