Two-Dimensional Biochemical Purification for Global Proteomic Analysis of Macromolecular Protein Complexes

: A high-resolution two-dimensional (2-D) proteomic fractionation technique for the systematic purification and subsequent mass spectrometry-based identification of endogenous protein macromolecular complexes is described. The method hyphenates preparative isoelectric focusing (IEF) with mixed-bed ion exchange chromatography (IEX) to efficiently separate cell- or tissue- derived soluble protein mixtures, allowing for more effective and less biased physiochemical characterization of stable multiprotein assemblies. After comprehensive 2D fractionation of cell-free lysates, each fraction is subjected to quantitative tandem mass spectrometry (MS/MS) and subsequent computational analysis to map high-confidence protein-protein interactions (PPIs). Herein, the experimental component (workflow protocols) for this global "interactome" network mapping platform is described.