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 (52): 50597-606

PMID: 12372823 · DOI:10.1074/jbc.M209037200

The interaction between nuclear pore proteins (nucleoporins) and transport factors is crucial for the translocation of macromolecules through nuclear pores. Many nucleoporins contain FG sequence repeats, and previous studies have demonstrated interactions between repeats containing FxFG or GLFG cores and transport factors. The crystal structure of residues 1-442 of importin-beta bound to a GLFG peptide indicates that this repeat core binds to the same primary site as FxFG cores. Importin-beta-I178D shows reduced binding to both FxFG and GLFG repeats, consistent with both binding to an overlapping site in the hydrophobic groove between the A-helices of HEAT repeats 5 and 6. Moreover, FxFG repeats can displace importin-beta or its S. cerevisiae homologue, Kap95, bound to GLFG repeats. Addition of soluble GLFG repeats decreases the rate of nuclear protein import in digitonin-permeabilized HeLa cells, indicating that this interaction has a role in the translocation of carrier-cargo complexes through nuclear pores. The binding of GLFG and FxFG repeats to overlapping sites on importin-beta indicates that functional differences between different repeats probably arise from differences in their spatial organization.

MeSH Terms (16)

Active Transport, Cell Nucleus Amino Acid Sequence Animals beta Karyopherins Binding Sites Cloning, Molecular Crystallography, X-Ray Dogs Kinetics Models, Molecular Nuclear Pore Complex Proteins Peptide Fragments Protein Conformation Protein Structure, Secondary Recombinant Proteins Saccharomyces cerevisiae

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