Nuclear pore complexes: guardians of the nuclear genome.

摘要: The nuclear envelope (NE) is perforated by pore complexes (NPCs), which are large multiprotein channels mediating macromolecular import and export an active, signal-dependent process (Terry et al. 2007). Unlike other cellular transport channels, NPCs span a double lipid bilayer constituted the outer (ONM) inner membranes (INM) that fused at sites of NPC insertion. highly curved membrane energetically unstable thus pores play important structural role in maintaining integrity channels. Each has diameter ~ 50 nm, exhibits total molecular mass 60 MDa thought to contain more than 500 polypeptides (Beck 2004; Alber This number components result assembly multiple copies 30 different nucleoporins (Nups), give rise eight-fold symmetrical protein complex (Strambio-De-Castillia 2010). organized scaffold, anchored NE least three transmembrane Nups. Eight filaments extend from this core structure into cytoplasm nucleoplasm, latter being frequently referred as basket (Figure 1). In addition, central coated natively unfolded Nups containing up repeat motifs rich phenylalanine glycine residues (FG-repeats) (Alber 2007; Terry Wente 2009). These largely hydrophobic patches constitute channel transiently bind receptors during translocation cargo molecules across NPC. At same time establish efficient permeability barrier for macromolecules larger 30–40 kDa prevent uncontrolled mixing nucleoplasmic cytoplasmic components. Since trafficking various models physical properties have been discussed many excellent reviews Lim 2008; 2009; Strambio-De-Castillia 2010; Walde Kehlenbach Wozniak 2010), we will focus on biogenesis discuss its chromatin organization gene regulation. Figure 1 Composition