Crystal structures reveal transient PERK luminal domain tetramerization in endoplasmic reticulum stress signaling

EMBO J. 2015 Jun 3;34(11):1589-600. doi: 10.15252/embj.201489183. Epub 2015 Apr 28.


Stress caused by accumulation of misfolded proteins within the endoplasmic reticulum (ER) elicits a cellular unfolded protein response (UPR) aimed at maintaining protein-folding capacity. PERK, a key upstream component, recognizes ER stress via its luminal sensor/transducer domain, but the molecular events that lead to UPR activation remain unclear. Here, we describe the crystal structures of mammalian PERK luminal domains captured in dimeric state as well as in a novel tetrameric state. Small angle X-ray scattering analysis (SAXS) supports the existence of both crystal structures also in solution. The salient feature of the tetramer interface, a helix swapped between dimers, implies transient association. Moreover, interface mutations that disrupt tetramer formation in vitro reduce phosphorylation of PERK and its target eIF2α in cells. These results suggest that transient conversion from dimeric to tetrameric state may be a key regulatory step in UPR activation.

Keywords: ER stress; PERK; cell signaling; unfolded protein response.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cells, Cultured
  • Crystallography, X-Ray
  • Endoplasmic Reticulum Stress / physiology*
  • Eukaryotic Initiation Factor-2 / genetics
  • Eukaryotic Initiation Factor-2 / metabolism
  • Humans
  • Mice
  • Mice, Knockout
  • Phosphorylation / physiology
  • Protein Multimerization / physiology
  • Protein Structure, Quaternary
  • Protein Structure, Tertiary
  • Signal Transduction / physiology*
  • Unfolded Protein Response / physiology
  • eIF-2 Kinase / chemistry*
  • eIF-2 Kinase / genetics
  • eIF-2 Kinase / metabolism*


  • Eukaryotic Initiation Factor-2
  • EIF2AK3 protein, human
  • PERK kinase
  • eIF-2 Kinase

Associated data

  • PDB/4YZS
  • PDB/4YZY