Serine/threonine-protein kinase/endoribonuclease IRE1 - O75460 (ERN1_HUMAN)

 

Protein Feature View of PDB entries mapped to a UniProtKB sequence  

  • Number of PDB entries for O75460: 11
 
Function
Serine/threonine-protein kinase and endoribonuclease that acts as a key sensor for the endoplasmic reticulum unfolded protein response (UPR) (PubMed:11779464, PubMed:11175748, PubMed:12637535, PubMed:9637683, PubMed:21317875). In unstressed cells, the endoplasmic reticulum luminal domain is maintained in its inactive monomeric state by binding to the endoplasmic reticulum chaperone HSPA5/BiP (PubMed:21317875). Accumulation of misfolded protein in the endoplasmic reticulum causes release of HSPA5/BiP, allowing the luminal domain to homodimerize, promoting autophosphorylation of the kinase domain and subsequent activation of the endoribonuclease activity (PubMed:21317875). The endoribonuclease activity is specific for XBP1 mRNA and excises 26 nucleotides from XBP1 mRNA (PubMed:11779464, PubMed:24508390, PubMed:21317875). The resulting spliced transcript of XBP1 encodes a transcriptional activator protein that up-regulates expression of UPR target genes (PubMed:11779464, PubMed:24508390, PubMed:21317875). Acts as an upstream signal for ER stress-induced GORASP2-mediated unconventional (ER/Golgi-independent) trafficking of CFTR to cell membrane by modulating the expression and localization of SEC16A (PubMed:21884936, PubMed:28067262). UniProt
Catalytic Activity
ATP + L-threonyl-[protein] = ADP + H+ + O-phospho-L-threonyl-[protein] UniProt
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Subunit Structure
Monomer (PubMed:29198525, PubMed:16973740). Homodimer; disulfide-linked; homodimerization takes place in response to endoplasmic reticulum stress and promotes activation of the kinase and endoribonuclease activities (PubMed:12637535, PubMed:24508390, PubMed:16973740, PubMed:21317875). Dimer formation is driven by hydrophobic interactions within the N-terminal luminal domains and stabilized by disulfide bridges (PubMed:12637535). Interacts (via the luminal region) with DNAJB9/ERdj4; interaction takes place in unstressed cells and promotes recruitment of HSPA5/BiP (PubMed:29198525). Interacts (via the luminal region) with HSPA5/BiP; HSPA5/BiP is a negative regulator of the unfolded protein response (UPR) that prevents homodimerization of ERN1/IRE1 and subsequent activation of the protein (PubMed:12637535, PubMed:29198525). Interacts with PDIA6, a negative regulator of the UPR; the interaction is direct and disrupts homodimerization (PubMed:24508390). Interacts with DAB2IP (via PH domain); the interaction occurs in a endoplasmic reticulum stress-induced dependent manner and is required for subsequent recruitment of TRAF2 to ERN1/IRE1 (By similarity). Interacts with TAOK3 and TRAF2 (PubMed:11278723). UniProt
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Data in green originates from UniProtKB  
Variation data (sourced from UniProt) shows non-genetic variation from the ExPASy   and dbSNP   websites.
Data in yellow originates from Pfam  , by interacting with the HMMER3 web site  
Data in purple originates from Phosphosite  .
Data in orange originates from the SCOP   (version 1.75) and SCOPe   (version 2.04) classifications.
Data in grey has been calculated using BioJava  . Protein disorder predictions are based on JRONN (Troshin, P. and Barton, G. J. unpublished), a Java implementation of RONN  
  • Red: potentially disorderd region
  • Blue: probably ordered region.
Hydropathy has been calculated using a sliding window of 15 residues and summing up scores from standard hydrophobicity tables.
  • Red: hydrophobic
  • Blue: hydrophilic.
Data in lilac represent the genomic exon structure projected onto the UniProt sequence.
Data in blue originates from PDB
  • Secstruc: Secondary structure projected from representative PDB entries onto the UniProt sequence.
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The PDB to UniProt mapping is based on the data provided by the EBI SIFTS project. See also Velankar et al., Nucleic Acids Research 33, D262-265 (2005).
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