Karyopherin flexibility in nucleocytoplasmic transport

Curr Opin Struct Biol. 2006 Apr;16(2):237-44. doi: 10.1016/j.sbi.2006.03.010. Epub 2006 Mar 29.


Recent structural work on nuclear transport factors of the importin-beta superfamily of karyopherins has shown that these proteins are superhelices of HEAT repeats that are able to assume different conformations in different functional states. The inherent flexibility of these helicoids facilitates the accommodation of different binding partners by an induced-fit type of mechanism. Moreover, the energy stored by distorting these molecules may partially balance binding energies to enable assembly and disassembly of their complexes with relatively small energy changes. Flexibility appears to be an intrinsic feature of such superhelices and might be functionally important not only for karyopherins and nuclear transport, but also for HEAT repeat proteins from other biological systems.

Publication types

  • Review

MeSH terms

  • Active Transport, Cell Nucleus
  • Animals
  • Crystallography, X-Ray
  • Humans
  • Karyopherins / chemistry*
  • Karyopherins / metabolism
  • Microscopy, Electron
  • Models, Molecular*
  • Nuclear Pore Complex Proteins / chemistry
  • Nuclear Pore Complex Proteins / metabolism
  • Protein Binding
  • Protein Conformation
  • Scattering, Radiation
  • X-Rays
  • ran GTP-Binding Protein / chemistry
  • ran GTP-Binding Protein / metabolism


  • Karyopherins
  • Nuclear Pore Complex Proteins
  • ran GTP-Binding Protein