The nuclear pore complex (NPC) is one of the most intricate components of eukaryotic cells and is assembled from ~30 Nucleoporins (Nups) in an unknown manner. Here I present an experimental result driven hypothesis, namely that the composition of the NPC varies across human cell types. As a consequence, the nucleocytoplasmic transport system might be fine-tuned to fulfill specific tasks in various cell types and to adjust the composition of the nuclear compartment. In the research proposed here, cell-type specific structural changes of NPCs will be monitored using systems approaches. The strength of single molecule methods such as cryo electron tomography (cryoET) will be synergistically combined with the strength of mass spectrometry (MS) to measure protein dynamics across cellular states. The outcome will be an atlas of the human NPC containing cell-type and functional state specific structural properties, namely nucleoporin copies per NPC, spatial restraints of protein interfaces, subunit positioning, and shape information. This research will facilitate the generation of a common structural modeling framework by providing the critical information of composition and spatial arrangement. It will furthermore elucidate how NPC composition and structure is adjusted as a function of the biological state of the cell. The long term goal is to integrate the different types of structural data using fitting, docking, and topological modeling approaches in order to project functionally specific compositional data onto structural models of the human NPC.