ATF6

During times of cellular stress overloading of the protein folding machinery leads to the accumulation of incorrectly folded proteins. This triggers the unfolded protein response (UPR) in order to try to reestablish homeostasis or, if this fails, to induce apoptosis. The UPR pathway is mediated by a group of ER-associated transmembrane receptors including activating transcription factor 6 (ATF6). The presence of misfolded proteins is monitored by BiP, an Hsp70 family member.

The protein ATF6 is a constitutively expressed transcription factor that is a key mediator of the unfolded protein response (UPR) that allows mammalian cells to maintain cellular homeostasis under conditions of environmental and physiological stress. ATF6 is endoplasmic reticulum (ER) membrane-anchored in its inactive form, and under certain stress conditions, translocates to the Golgi where it is processed into its active form through action of the S1P and S2P proteases.