ATFC is a novel transducer for the unfolded protein response in Bombyx mori BM5 cells

We report the isolation of activating transcription factor of chaperone (ATFC), a novel cDNA from Bombyx mori BM5 cells that encodes a putative transducer of endoplasmic reticulum (ER) stress. The 236 amino acids of ATFC include both a basic region and a leucine zipper at the C-terminus, in contrast to Hac1p of yeast which features these structures at its N-terminus. ATFC expression was strongly up-regulated by ER stress. ATFC could specifically bind to the unfolded protein response element. BM5 cells transfected with ATFC cDNA displayed enhanced ER chaperone expression in response to ER stress. These results indicate that ATFC encodes a putative transducer of ER stress.