Abstract
Proteins synthesized in the endoplasmic reticulum (ER) are correctly folded before translocation. If protein folding is incorrect, genes for ER-resident chaperones such as BiP are induced. This phenomenon is known as the ER stress response or the unfolded protein response (UPR). Studying molecular mechanism of the ER stress response in Arabidopsis, we identified a bZIP transcription factor, AtbZIP60, induced by an ER stress inducer tunicamycin. AtbZIP60 has a putative transmembrane domain in its C-terminal region, suggesting proteolysis triggers its activation. Immunoblot analysis indicated that AtbZIP60 protein was cleaved by tunicamycin and DTT treatment. Subcellular fractionation showed that full-length and cleaved AtbZIP60 localized to the ER and the nucleus, respectively, supporting the above hypothesis. In order to investigate the physiological role of AtbZIP60, detection of cleaved AtbZIP60 under normal growth condition will be tested.
