Function
Transcription factor involved in unfolded protein response (UPR). In the absence of endoplasmic reticulum (ER) stress, inserted into ER membranes, with N-terminal DNA-binding and transcription activation domains oriented toward the cytosolic face of the membrane. In response to ER stress, transported to the Golgi, where it is cleaved in a site-specific manner by resident proteases S1P/MBTPS1 and S2P/MBTPS2. The released N-terminal cytosolic domain is translocated to the nucleus to effect transcription of specific target genes. Plays a critical role in chondrogenesis by activating the transcription of SEC23A, which promotes the transport and secretion of cartilage matrix proteins, and possibly that of ER biogenesis-related genes. In a neuroblastoma cell line, protects cells from ER stress-induced death. In vitro activates transcription of target genes via direct binding to the CRE site.
Tissue Specificity
Widely expressed with highest levels in placenta, lung, spleen and intestine, and lowest levels in heart, brain, skeletal muscle, thymus, colon and leukocytes. In fetal tissues, the weakest expression is detected in brain and heart.
