Steady-state nuclear localization of exportin-t involves RanGTP binding and two distinct nuclear pore complex interaction domains

Mol Cell Biol. 2002 Aug;22(16):5708-20. doi: 10.1128/MCB.22.16.5708-5720.2002.

Abstract

Vertebrate tRNA export receptor exportin-t (Xpo-t) binds to RanGTP and mature tRNAs cooperatively to form a nuclear export complex. Xpo-t shuttles bidirectionally through nuclear pore complexes (NPCs) but is mainly nuclear at steady state. The steady-state distribution of Xpo-t is shown to depend on its interaction with RanGTP. Two distinct Xpo-t NPC interaction domains that bind differentially to peripherally localized nucleoporins in vitro are identified. The N terminus binds to both Nup153 and RanBP2/Nup358 in a RanGTP-dependent manner, while the C terminus binds to CAN/Nup214 independently of Ran. We propose that these interactions increase the concentration of tRNA export complexes and of empty Xpo-t in the vicinity of NPCs and thus increase the efficiency of the Xpo-t transport cycle.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Active Transport, Cell Nucleus / physiology*
  • Animals
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • HeLa Cells
  • Humans
  • Microinjections
  • Models, Biological
  • Nuclear Pore / metabolism*
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Nucleocytoplasmic Transport Proteins*
  • Oocytes
  • Protein Binding
  • Protein Structure, Tertiary
  • RNA, Transfer / metabolism
  • Xenopus laevis
  • ran GTP-Binding Protein / metabolism*

Substances

  • Carrier Proteins
  • Nuclear Proteins
  • Nucleocytoplasmic Transport Proteins
  • XPOT protein, human
  • RNA, Transfer
  • ran GTP-Binding Protein