Characterization of two homologs of Ire1p, a kinase/endoribonuclease in yeast, in Arabidopsis thaliana.
The accumulation of unfolded proteins in the endoplasmic reticulum (ER) elicits an ER-to-nucleus signaling pathway known as the unfolded protein response (UPR) in eukaryotes. In yeast, Ire1p, a kinase/endoribonuclease in the ER membrane, plays a key role in the UPR signaling. We isolated two cDNA homologs of IRE1 gene from Arabidopsis (AtIre1a, AtIre1b). The two IRE1 homologs were predicted to form a type I transmembrane protein structure and contain kinase/endoribonuclease domains at their C-terminal halves. The expressions of the two genes were detected in various organ tissues of the Arabidopsis plant. The C-terminal half of the AtIre1a protein showed in vitro autophosphorylation activity. However, we could not detect endoribonuclease activity of the AtIre1a protein when we used yeast HAC1 RNA as the substrate in vivo.
Noh
Seung-Jae
SJ
Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 371-1, Kusong-dong, Yusong-gu, Taejon 305-701, South Korea.
Kwon
Chang Seob
CS
Chung
Won-Il
WI
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D020033:Protein Isoforms / Q000235:genetics; D011494:Protein Kinases / Q000235:genetics* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D016415:Sequence Alignment
D029681:Arabidopsis Proteins; D008565:Membrane Proteins; D020033:Protein Isoforms; D011494:Protein Kinases; C446527:Ire1-1 protein, Arabidopsis; C446528:Ire1-2 protein, Arabidopsis