3P23 image
Deposition Date 2010-10-01
Release Date 2011-02-23
Last Version Date 2024-02-21
Entry Detail
PDB ID:
3P23
Title:
Crystal structure of the Human kinase and RNase domains in complex with ADP
Biological Source:
Source Organism:
Homo sapiens (Taxon ID: 9606)
Host Organism:
Method Details:
Experimental Method:
Resolution:
2.70 Å
R-Value Free:
0.29
R-Value Work:
0.23
R-Value Observed:
0.23
Space Group:
P 1 21 1
Macromolecular Entities
Polymer Type:polypeptide(L)
Molecule:Serine/threonine-protein kinase/endoribonuclease IRE1
Gene (Uniprot):ERN1
Chain IDs:A, B, C, D
Chain Length:432
Number of Molecules:4
Biological Source:Homo sapiens
Primary Citation
Structure of the Ire1 autophosphorylation complex and implications for the unfolded protein response.
Embo J. 30 894 905 (2011)
PMID: 21317875 DOI: 10.1038/emboj.2011.18

Abstact

Ire1 (Ern1) is an unusual transmembrane protein kinase essential for the endoplasmic reticulum (ER) unfolded protein response (UPR). Activation of Ire1 by association of its N-terminal ER luminal domains promotes autophosphorylation by its cytoplasmic kinase domain, leading to activation of the C-terminal ribonuclease domain, which splices Xbp1 mRNA generating an active Xbp1s transcriptional activator. We have determined the crystal structure of the cytoplasmic portion of dephosphorylated human Ire1α bound to ADP, revealing the 'phosphoryl-transfer' competent dimeric face-to-face complex, which precedes and is distinct from the back-to-back RNase 'active' conformation described for yeast Ire1. We show that the Xbp1-specific ribonuclease activity depends on autophosphorylation, and that ATP-competitive inhibitors staurosporin and sunitinib, which inhibit autophosphorylation in vitro, also inhibit Xbp1 splicing in vivo. Furthermore, we demonstrate that activated Ire1α is a competent protein kinase, able to phosphorylate a heterologous peptide substrate. These studies identify human Ire1α as a target for development of ATP-competitive inhibitors that will modulate the UPR in human cells, which has particular relevance for myeloma and other secretory malignancies.

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