In order to understand how a nucleoporin carries out multiple functions, we are using Nup153 as a paradigm and taking several approaches. First, we are studying known partnerships in molecular detail. This goal led to a collaboration with the Sundquist lab at the University of Utah in which the structure of a zinc finger from Nup153 was solved using NMR. We then probed the interaction between the small GTPase Ran and this Nup zinc finger domain (Higa et al., 2007). This study provided insight into how particular amino acids within this ZnF platform dictate partner specificity. Secondly, we have performed knockdown/rescue experiments in cultured human cells to both further define the roles of Nup153 in somatic cells and to assign phenotypes to specific domains (Mackay et al., 2009; Mackay et al., 2010b). We have also established an inducible expression system in mammalian cells to assess dominant interfering phenotypes. One interesting observation using this approach has been the finding that overexpression of the Nup153 C-terminal domain interferes with nuclear pore basket assembly (Mackay et al, 2010b), which is a new clue to the role of Nup153 in this process. Finally, in collaboration with Prolexys Pharmaceuticals, we undertook a partner protein analysis of Nup153. Proteins found in this screen are attractive candidates for linking Nup153 to its various roles and we are pursuing ones of interest.