ATF6 

ATF6 (Activating transcription factor 6) is an endoplasmic reticulum (ER)-localised protein and member of the leucine zipper family of transcription factors. ATF6 plays an important role in transducing signals linked to the ER stress. In the absence of ER stress, GRP78 binds to the ER luminal domain of ATF6 and anchors ATF6 in the ER. Upon ER stress, GRP78 dissociates from, and thus, releases ATF6, allowing it to relocate to the next destination in the secretory pathway, the Golgi. In the Golgi, ATF6 is cleaved by S1P and S2P proteases by regulated intramembrane proteolysis. This cleavage liberates the N-terminal 50 kD cytosolic portion of ATF6 (activated form), which has a nuclear localization sequence, facilitating its movement to the nucleus, where it acts as a transcription factor to induce genes that encode stress-reducing chaperones and foldases that slow the pace of protein translation.