CRM1 mediates one of the major nuclear export pathways with the broadest range of cargoes. So far, more than 100 structurally and functionally diverse CRM1 cargoes have been described. We employed affinity purification mass spectrometry for in depth characterization of CRM1 "exportome" in three model systems and we identified surprisingly large numbers, namely >700 export substrates from the yeast S. cerevisiae, ≈ 1000 from Xenopus oocytes and >1050 from human cells.I. Futher, we quantified the partitioning of ≈9600 proteoforms between nucleus and cytoplasm of Xenopus oocytes.