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The nuclear pore complex (NPC) constitutes one of the largest protein assemblies in the eukaryotic cell and forms the exclusive gateway to the nucleus. The stable, approximately 15-20-MDa scaffold ring of the NPC is built from two multiprotein complexes arranged around a central 8-fold axis. Here we present crystal structures of two large architectural units, yNup170(979-1502) and hNup107(658-925) x hNup133(517-1156), each a constituent of one of the two multiprotein complexes. Conservation of domain arrangement and of tertiary structure suggests that Nup157/170 and Nup133 derived from a common ancestor. Together with the previously established ancestral coatomer element (ACE1), these two elements constitute the major alpha-helical building blocks of the NPC scaffold and define its branched, lattice-like architecture, similar to vesicle coats like COPII. We hypothesize that the extant NPC evolved early during eukaryotic evolution from a rudimentary structure composed of several identical copies of a few ancestral elements, later diversified and specified by gene duplication.

Citation

James R R Whittle, Thomas U Schwartz. Architectural nucleoporins Nup157/170 and Nup133 are structurally related and descend from a second ancestral element. The Journal of biological chemistry. 2009 Oct 9;284(41):28442-52

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PMID: 19674973

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