http://www.sciencedirect.com – The basic structure of the nuclear pore complex (NPC), conserved across almost all organisms from yeast to humans, persists in featuring an octagonal symmetry involving the nucleoporins that constitute the NPC ring. In this article, we seek to understand and evaluate the potential biomechanical reasons for this eightfold symmetry. Our analytical investigation shows that the eightfold symmetry maximizes the bending stiffness of each of the eight NPC spokes while our computational analyses identify the most likely deformation modes, frequencies, and associated kinetic energies of the NPC. Read more »

http://www.ploscompbiol.org – The nuclear pore complex (NPC) is the gate to the nucleus. Recent determination of the configuration of proteins in the yeast NPC at ~5 nm resolution permits us to study the NPC global dynamics using coarse-grained structural models. We investigate these large-scale motions by using an extended elastic network model (ENM) formalism applied to several coarse-grained representations of the NPC. Two types of collective motions (global modes) are predicted by the ENMs to be intrinsically favored by the NPC architecture: global bending and extension/contraction from circular to elliptical shapes. Read more »

http://www.sciencedirect.com – In eukaryotes, all macromolecules traffic between the nucleus and the cytoplasm through nuclear pore complexes (NPCs), which are among the largest supramolecular assemblies in cells. Although their composition in yeast and metazoa is well characterized, understanding how NPCs are assembled and form the pore through the double membrane of the nuclear envelope and how both processes are controlled still remains a challenge. Read more »

http://www.sciencedirect.com – Nuclear pore complexes (NPCs) mediate all selective bidirectional transport between the nucleus and the cytoplasm. Additional functions for NPCs and their constituent proteins (nucleoporins) are emerging, some independent of classical transport. Specifically, enzymatic activities at the NPC regulate nucleocytoplasmic transport and use the NPC as a regulatory scaffold. Also, nucleoporins may regulate gene expression by contacting chromatin. Read more »

http://www.pubmedcentral.nih.gov – The nuclear pore supports molecular communication between cytoplasm and nucleus in eukaryotic cells. Selective transport of proteins is mediated by soluble receptors, whose regulation by the small GTPase Ran leads to cargo accumulation in, or depletion from, the nucleus, i.e., nuclear import or nuclear export. We consider the operation of this transport system by a combined analytical and experimental approach. Provocative predictions of a simple model were tested using cell-free nuclei reconstituted in Xenopus egg extract, a system Read more »

http://www.sciencemag.org – Transport of macromolecules between the nucleus and cytoplasm is a critical cellular process for eukaryotes, and the machinery that mediates nucleocytoplasmic exchange is subject to multiple levels of control. Regulation is achieved by modulating the expression or function of single cargoes, transport receptors, or the transport channel. Each of these mechanisms has increasingly broad impacts on transport patterns and capacity, and this hierarchy of control directly affects gene expression, signal transduction, development, and disease. Read more »

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round things--spiritual source. Is a painting hanging in the front. Work was divided into four parts. But as if each of the missing things. Although I don't understand what does that picture. No one in the room, the witch was not at home. Within the whole room is not ornate. Is the wooden walls on either side, and opened a door on both sides, I opened the door--was a side fit, which stood a wooden table, a magnificent bed, a wardrobe. Tables had been placed on a wooden tray, containing blueberries. She is not white stones that block put on themselves. Read more »

http://jcb.rupress.org – An understanding of how the nuclear pore complex (NPC) mediates nucleocytoplasmic exchange requires a comprehensive inventory of the molecular components of the NPC and a knowledge of how each component contributes to the overall structure of this large molecular translocation machine. Therefore, we have taken a comprehensive approach to classify all components of the yeast NPC (nucleoporins). This involved identifying all the proteins present in a highly enriched NPC fraction, determining which of these proteins were nucleoporins, and localizing each nucleoporin within the NPC. Read more »