Nuclear pore complexes form a selective filter that allows the rapid passage of transport factors and their cargoes across the nuclear envelope, while blocking the passage of other macromolecules. Intrinsically disordered proteins (IDPs) containing phenylalanyl-glycyl (FG) rich repeats line the pore and interact with transport factors. However, the reason that transport can be both fast and specific remains undetermined, through lack of atomic-scale information on the behavior of FGs and their interaction with transport factors. We recently showed that the interactions between FG Nups and transport factors is extremely transient, with the protein remaining fully disordered upon binding (Hough et. al. eLife 2015). We have continued to test the behavior of these proteins and their interactions with transport factors. For example, we have shown that they behave similarly within the cytoplasm of yeast as they do within living bacteria.