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| J. Cell. Sci. May (2007); 120:1681-8 | |
| Self-association and BiP dissociation are not sufficient for activation of the ER stress sensor Ire1- | |
| Oikawa D, Kimata Y, Kohno K | |
| Laboratory of Molecular and Cell Genetics, Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan- | |
| Abstract: Ire1 is a type I transmembrane protein located on the endoplasmic reticulum -ER-- Upon ER stress, Ire1 releases the ER chaperone BiP and self-associates- This activates Ire1 and triggers the unfolded protein response in the yeast Saccharomyces cerevisiae- We isolated and characterized an Ire1 luminal domain mutant lacking both the N-terminal and the juxtamembrane loosely folded subregions- Although this 'core' mutant was able to self-associate and failed to bind BiP even under nonstressed conditions, its activation was still dependent on ER stress- Furthermore, although substitution of Pro for Ser103 -S103P- in the luminal domain of full-length Ire1 caused neither BiP dissociation nor a change in self-association, the substitution in combination with the core mutation resulted in constitutive activation- This phenotype of the S103P mutation required a cluster of positively charged amino acid residues -Arg or Lys- located close to the mutation site in the Ire1 sequence- These observations indicate that in addition to BiP dissociation and self-association of Ire1, another unknown change on the luminal side is crucial for Ire1 activation- | |
| [PUBMED: 17452628] |   |
| Copyright © 2009, Tyers Lab, The Samuel Lunenfeld Research Institute, Mount Sinai Hospital, All Rights Reserved. |
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| BioGRID: A General Repository for Interaction Datasets. Chris Stark, Bobby-Joe Breitkreutz, Teresa Reguly, Lorrie Boucher, Ashton Breitkreutz, Mike Tyers. Nucleic Acids Res. Jan 1;34:D535-9. |