Phosphoproteomics reveals new ERK MAP kinase targets and links ERK to nucleoporin-mediated nuclear transport

Nat Struct Mol Biol. 2009 Oct;16(10):1026-35. doi: 10.1038/nsmb.1656. Epub 2009 Sep 20.


Many extracellular signal-regulated kinase (ERK) mitogen-activated protein (MAP) kinase substrates have been identified, but the diversity of ERK-mediated processes suggests the existence of additional targets. Using a phosphoproteomic approach combining the steroid receptor fusion system, IMAC, 2D-DIGE and phosphomotif-specific antibodies, we detected 38 proteins showing reproducible phosphorylation changes between ERK-activated and ERK-inhibited samples, including 24 new candidate ERK targets. ERK directly phosphorylated at least 13 proteins in vitro. Of these, Nup50 was verified as a bona fide ERK substrate. Notably, ERK phosphorylation of the FG repeat region of Nup50 reduced its affinity for importin-beta family proteins, importin-beta and transportin. Other FG nucleoporins showed a similar functional change after ERK-mediated phosphorylation. Nuclear migration of importin-beta and transportin was impaired in ERK-activated, digitonin-permeabilized cells, as a result of ERK phosphorylation of Nup50. Thus, we propose that ERK phosphorylates various nucleoporins to regulate nucleocytoplasmic transport.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Active Transport, Cell Nucleus
  • Animals
  • Cell Nucleus / metabolism
  • Cytoplasm / metabolism
  • Electrophoresis, Gel, Two-Dimensional
  • Extracellular Signal-Regulated MAP Kinases / metabolism*
  • Humans
  • Karyopherins / metabolism
  • Mice
  • NIH 3T3 Cells
  • Nuclear Pore Complex Proteins / chemistry*
  • Phosphoproteins / chemistry
  • Phosphoproteins / physiology*
  • Phosphorylation
  • Proteomics / methods*
  • beta Karyopherins / metabolism


  • Karyopherins
  • Nuclear Pore Complex Proteins
  • Phosphoproteins
  • beta Karyopherins
  • Extracellular Signal-Regulated MAP Kinases