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Abstract

Identification and characterization of multi-protein complexes is an important step toward an integrative view of protein-protein interaction networks that determine protein function and cell behavior. The limiting factor for identifying protein complexes is the method for their separation. Blue native PAGE (BN-PAGE) permits a high-resolution separation of multi-protein complexes under native conditions. To date, BN-PAGE has only been applicable to purified material. Here, we show that dialysis permits the analysis of multi-protein complexes of whole cellular lysates by BN-PAGE. We visualized different multi-protein complexes by immunoblotting including forms of the eukaryotic proteasome. Complex dynamics after γ interferon stimulation of cells was studied, and an antibody shift assay was used to detect protein-protein interactions in BN-PAGE. Furthermore, we identified defined protein complexes of various proteins including the tumor suppressor p53 and c-Myc. Finally, we identified multi-protein complexes via mass spectrometry, showing that the method has a wide potential for functional proteomics.