text: When a cell is subjected to stressful conditions, the ATF4 gene is expressed. The ATF4 transcription factor has the ability to form dimers with many different proteins that influence gene expression and cell fate. ATF4 binds to C/EBP‐ATF response element (CARE) sequences which work together to increase the transcription of stress-responsive genes. However, when undergoing amino acid starvation, the sequences will act as amino acid response elements instead.
  ATF4 will work together with other transcription factors, such as CHOP and ATF3, by forming homodimers or heterodimers, resulting in numerous observed effects. The proteins that ATF4 interacts with determines the outcome of the cell during the integrated stress response. For example, ATF4 and ATF3 work to establish homeostasis inside of the cell following stressful conditions. On the other hand, ATF4 and CHOP work together to induce cell death, as well as regulating amino acid biosynthesis, transport and metabolic processes. The presence of a leucine zipper domain (bZIP) allows ATF4 to work together with many other proteins, thus creating specific responses to different types of stressors. When a cell is undergoing the stress of hypoxia, ATF4 will interact with PHD1 and PHD3 to decrease its transcriptional activity. In addition, when a cell is undergoing amino acid starvation or endoplasmic reticulum stress, TRIP3 also interacts with ATF4 to decrease activity. 
  One result of ATF4 and stress-response proteins expression is the induction of autophagy. During this process, the cell forms autophagosomes, or double membraned vesicles, that allow for transportation of material throughout the cell. These autophagosomes can carry unneeded organelles and proteins, as well as damaged or harmful components in an attempt by the cell to maintain homeostasis.