Cellular processes depend on physical associations between proteins; these same interaction networks are often disrupted by mutations, disease, or drugs. Yet despite progress, particularly by research groups at HMS, knowledge of the myriad of macromolecules present in different cells and tissues remains limited, especially regarding the effects of developmental, environmental or small molecule perturbations. To close this gap, my laboratory develops and applies systematic proteomic approaches to characterize native multiprotein complexes in diverse cell systems. The resulting protein interaction maps provide fundamental insights into (human) cell biology, protein function and the modular physical architecture underlying evolutionarily conserved processes.