ATF - or Activating Transcription Factor - refers to a specific group of bZIP transcription factors. There are many genes that fall under the ATF category, including ATF1, ATF2, ATF3, ATF4, ATF5, ATF6, ATF7, and ATFx,
Generally speaking, all ATFs are believed to be highly responsive to extracellular signals. As such, many suggest this means they have a key role to play in homeostasis. However, different ATF genes also have some specific roles/functions, such as stress response or apoptosis suppression.
All members of the ATF have been considered members of the CREB/ATF family. When first discovered, it was believed they possessed a similar structure to this family. However, it was later revealed that they were actually structurally more similar to AP-1 factors. As such, many members of the ATF family bare a similar structure to factors such as c-Jun or c-Fos. The precise structure of each individual activating transcription factor is difficult to see. They vary so much and have so many interactions, it's hard to pinpoint precisely what each one looks like. However, we can provide a bit of information on ATF2 and ATF5.
Each ATF has a different structure. ATF2 has a total of 505 amino acids and is found at human chromosome 2q32. ATF5 is said to have 282 amino acids in its protein.
Activating Transcription Factor Mechanism
The general way that ATF works is by responding to various extracellular signals throughout the body. Each gene in this group has its own mechanism to take care of. For example, ATF1 influences the physiologic process. It regulates the expression of genes that are linked to growth, survival, and many other cellular activities. ATF2 binds to the cAMP-responsive element, an octameric palindrome. Here, it forms a homodimer or heterodimer with c-jun. From this, it stimulates CRE-dependant transcription.
Each gene has its own capacity where it plays a specific role. In ATF4, the service is to help with osteoblast differentiation. ATF3 is found to be induced upon physiological stress in some tissues in the body. What's more, it's also seen to signify regeneration after an injury to dorsal root ganglion neurons. Therefore, this activating transcription factor is thought to help encourage the regeneration of peripheral neurons.
ATF1 is seen to help enhance cell transformation. This happens when it phosphorizes as this increases its transactivation and transcriptional activities. ATF transcripts and proteins are found in lots of tissues throughout the body. It's particularly prevalent in the liver. You will find ATF5 in VZ and SVZ during brain development as well. ATF6 is an endoplasmic reticulum stress-regulated transmembrane transcription factor. In essence, it helps activate the transcription of ER molecules.
The interactions of the activating transcription factor are plentiful. Each member of the family interacts with different elements in various tissues. Below, we've listed what each member interacts with:
● ATF1: BRCA1, CSNK2A2, CSNK2AI, EWS
● ATF2: C-jun, Casein kinase 2, CREB binding protein, CSN2A2, JDP2, MAPK14, MAPK8, NCOA6, RUVBL2, UBE2I
● ATF3: DDIT3, SMAD3, JunD, P53, C-jun
● ATF4: RUNX2, osterix, JNK
● ATF5: DISC1, TRIB3
● ATF6: YY1, Serum response factor
● ATF7: PTP4A1