Yeast and vertebrate nuclear-pore complexes: evolutionary conserved, yet divergent macromolecular assemblies

The nuclear-pore complex (NPC), which consists of ca, 50 proteins called nucleoporins, is a huge macromolecular structure that spans the nuclear envelope and is an obligatory passage for molecules in transit between the cytoplasm and the nucleus. In the last years, major progress has allowed the characterization of the so-called "soluble phase" of nucleocytoplasmic transport, that involves transport substrates, import and export receptors of which some belong to the karyopherin-beta family, and the small GTPase Ran and its modulators. In addition, the knowledge of the NPC architecture, the identification of its constituents, and the determination of the hierarchy of interactions within the pore should help to understand how nucleoporins are assembled, and how they give rise to a functional NPC through interactions with specific transport factors. In this review, we will focus on recent insights into the stationary phase of nucleocytoplasmic transport (i.e., the NPCs) that have been gained from exploiting the benefits of several organisms, such as Xenopus laevis oocytes, mammalian cell lines, and the yeast Saccharomyces cerevisiae.