Translation and translocation of XBP1(S) to the Nucleus

Reviewed: D'Eustachio, P, Matthews, L, Gillespie, ME, 2008-12-02 16:25:31 Phosphorylated IRE1-alpha homodimers with bound ADP have endoribonuclease activity in their C-terminal (cytosolic) regions. In particular, the homodimers cleave an internal 26 nucleotide segment out of the Xbp-1 mRNA. In yeast the resulting RNAs are ligated by a tRNA ligase but the corresponding human enzyme has not been identified. The cleavage and ligation leads to a frameshift which results in a longer ORF that encodes Xbp-1 (S), the active form of the Xbp-1 transcription factor.<br>The ribonuclease activity of IRE1-alpha also degrades subsets of mRNAs in the vicinity of the ER membrane, thereby reducing the amount of protein entering the ER.<br>Xbp-1 mRNA that has been cleaved by IRE1-alpha encodes a 40 kd protein designated Xbp-1 (S). Xbp-1 (S) is a potent bZIP transcription factor that transits from the cytosol to the nucleus and binds the sequence CCACG in the ER Stress Responsive Element (ERSE). Reviewed: Urano, F, 2010-04-30 Authored: May, B, 2009-06-02 00:51:49 Edited: May, B, 2009-06-02 00:51:49

http://purl.obolibrary.org/obo/HINO_0008872

Reviewed: D'Eustachio, P, Matthews, L, Gillespie, ME, 2008-12-02 16:25:31

Phosphorylated IRE1-alpha homodimers with bound ADP have endoribonuclease activity in their C-terminal (cytosolic) regions. In particular, the homodimers cleave an internal 26 nucleotide segment out of the Xbp-1 mRNA. In yeast the resulting RNAs are ligated by a tRNA ligase but the corresponding human enzyme has not been identified. The cleavage and ligation leads to a frameshift which results in a longer ORF that encodes Xbp-1 (S), the active form of the Xbp-1 transcription factor.
The ribonuclease activity of IRE1-alpha also degrades subsets of mRNAs in the vicinity of the ER membrane, thereby reducing the amount of protein entering the ER.
Xbp-1 mRNA that has been cleaved by IRE1-alpha encodes a 40 kd protein designated Xbp-1 (S). Xbp-1 (S) is a potent bZIP transcription factor that transits from the cytosol to the nucleus and binds the sequence CCACG in the ER Stress Responsive Element (ERSE).

Reviewed: Urano, F, 2010-04-30

Authored: May, B, 2009-06-02 00:51:49

Edited: May, B, 2009-06-02 00:51:49

Pubmed16461360

Reactome, http://www.reactome.org

Pubmed11779464

Pubmed8657566

http://purl.obolibrary.org/obo/HINO_0025381

http://purl.obolibrary.org/obo/UniProt_P17861-2

Translation and translocation of XBP1(S) to the Nucleus

HINO:0008872

Translation and translocation of XBP1(S) to the Nucleus

ReactomeREACT_18336

Reactome Database ID Release 43381203

http://purl.obolibrary.org/obo/INO_0000040