Abstract
Proteins synthesized in the endoplasmic reticulum (ER) need to be correctly folded before translocation. If protein folding is incorrect, genes for the ER-resident chaperones such as BiP are induced. This phenomenon is known as the unfolded protein response (UPR). Recent studies indicated activation of genes for vesicle transport in the plant UPR. Our objective is elucidation of molecular mechanism of the UPR in plants. Since bZIP proteins play important roles in yeast and mammalian UPR, we screened bZIP genes of Arabidopsis and identified AtbZIPER that was highly induced in the UPR. A transmembrane domain in AtbZIPER suggested proteolysis for the activation. In fact, GFP fusion of truncated-AtbZIPER localized in the nucleus. In a T-DNA insertion mutant of AtbZIPER, a gene for the ER-to-Golgi transport induced in the UPR was clearly repressed. Further characterization of AtbZIPER will be presented.
