The lumen-facing domain is important for the biological function and organelle-to-organelle movement of bZIP28 during ER stress in Arabidopsis

Mol Plant. 2013 Sep;6(5):1605-15. doi: 10.1093/mp/sst059. Epub 2013 Apr 4.


The membrane-associated transcription factor, bZIP28, is relocated from the endoplasmic reticulum (ER) to the Golgi and proteolytically released from the membrane mediated by two proteases, S1P and S2P, in response to ER stress in Arabidopsis. The activated N-terminal domain recruits nuclear factor Y (NF-Y) subunits in the nucleus to regulate ER stress downstream genes. Little is known about the functions of the bZIP28 C-terminal lumen-facing domain. Here, we provide novel insights into how the ER lumen-facing domain affects the biological function and organelle-to-organelle movement of bZIP28 in the ER stress response. First, we demonstrated the functional redundancy of bZIP28 and bZIP60 by generation and analysis of the bZIP28 and bZIP60 double mutant zip28zip60. Subsequent genetic complementation experiments in zip28zip60 background with deletions on bZIP28 lumen-facing domain highlighted the importance of lumen-facing domain for its in vivo function of bZIP28 in the ER stress response. The protein subcellular localization and Western blotting results further revealed that the bZIP28 lumen-facing domain contains ER retention signal which is important for the proteolytic activation of bZIP28. Thus, the bZIP28 lumen-facing C-terminus plays important roles in the ER-to-Golgi movement of bZIP28, which may contribute to the sensing of the ER stress.

Keywords: ER stress response; ER-to-Golgi translocation; bZIP28; bZIP60; unfolded protein response..

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / drug effects
  • Arabidopsis / genetics
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / chemistry*
  • Arabidopsis Proteins / metabolism*
  • Basic-Leucine Zipper Transcription Factors / chemistry*
  • Basic-Leucine Zipper Transcription Factors / metabolism*
  • Endoplasmic Reticulum Stress* / drug effects
  • Gene Expression Regulation, Plant / drug effects
  • Genetic Complementation Test
  • Models, Biological
  • Mutation / genetics
  • Organelles / metabolism*
  • Phenotype
  • Protein Sorting Signals
  • Protein Structure, Tertiary
  • Protein Transport / drug effects
  • Structure-Activity Relationship
  • Subcellular Fractions / drug effects
  • Subcellular Fractions / metabolism
  • Tunicamycin / pharmacology
  • Unfolded Protein Response / drug effects
  • Unfolded Protein Response / genetics


  • Arabidopsis Proteins
  • Basic-Leucine Zipper Transcription Factors
  • Protein Sorting Signals
  • bZIP28 protein, Arabidopsis
  • bZIP60 protein, Arabidopsis
  • Tunicamycin