Taxonomic distribution of proteins containing IBN_N domains

The tree below includes only several representative species and genera. The complete taxonomic breakdown of all proteins containing IBN_N domains can be accessed here. Click the counts or percentage values to display the corresponding proteins.

Association of nuclear pore FG-repeat domains to NTF2 import and exportcomplexes.

Isgro TA, Schulten K
J Mol Biol. 2007; 366: 330-45

Transport into and out of the nucleus is regulated by the nuclear porecomplex. Vital to this regulation are nuclear pore proteins with FGsequence repeats, which have been shown to be crucial for cell viabilityand which interact with nuclear transport receptors. Here we use moleculardynamics simulations to investigate the binding of FG-repeat peptides tothe surface of NTF2, the Ran importer. The simulations, covering over 254ns, agree with previous X-ray, mutational, NMR, and computational data inidentifying four binding spots. They also serve to provide an all-atomview of binding at each spot, whereas FG-repeat binding has been onlydirectly observed at a single spot. Furthermore, the simulations identifytwo novel binding spots in addition to the four others. All six bindingspots broadly form a stripe across the surface of NTF2. The resultingregularity and proximity of binding spots on the surface may be necessaryfor identification of the transport receptor by the FG-repeats in thenuclear pore complex and for the successful transit of NTF2 through thepore.

GLFG and FxFG nucleoporins bind to overlapping sites on importin-beta.

Bayliss R, Littlewood T, Strawn LA, Wente SR, Stewart M
J Biol Chem. 2002; 277: 50597-606

The interaction between nuclear pore proteins (nucleoporins) and transportfactors is crucial for the translocation of macromolecules through nuclearpores. Many nucleoporins contain FG sequence repeats, and previous studieshave demonstrated interactions between repeats containing FxFG or GLFGcores and transport factors. The crystal structure of residues 1-442 ofimportin-beta bound to a GLFG peptide indicates that this repeat corebinds to the same primary site as FxFG cores. Importin-beta-I178D showsreduced binding to both FxFG and GLFG repeats, consistent with bothbinding to an overlapping site in the hydrophobic groove between theA-helices of HEAT repeats 5 and 6. Moreover, FxFG repeats can displaceimportin-beta or its S. cerevisiae homologue, Kap95, bound to GLFGrepeats. Addition of soluble GLFG repeats decreases the rate of nuclearprotein import in digitonin-permeabilized HeLa cells, indicating that thisinteraction has a role in the translocation of carrier-cargo complexesthrough nuclear pores. The binding of GLFG and FxFG repeats to overlappingsites on importin-beta indicates that functional differences betweendifferent repeats probably arise from differences in their spatialorganization.