Basic leucine zipper (bZIP) domain of large musculoaponeurotic fibrosarcoma (Maf) proteins: a DNA-binding and dimerization domain
Maf proteins are Basic leucine zipper (bZIP) transcription factors that may participate in the activator protein-1 (AP-1) complex, which is implicated in many cell functions including proliferation, apoptosis, survival, migration, tumorigenesis, and morphogenesis, among others. Maf proteins fall into two groups: small and large. The large Mafs (c-Maf, MafA, MafB, and neural retina leucine zipper or NRL) contain an N-terminal transactivation domain, a linker region of varying size, an anxillary DNA-binding domain, a C-terminal bZIP domain. They function as critical regulators of terminal differentiation in the blood and in many tissues such as bone, brain, kidney, pancreas, and retina. MafA and MafB also play crucial roles in islet beta cells; they regulate genes essential for glucose sensing and insulin secretion cooperatively and sequentially. Large Mafs are also implicated in oncogenesis; MafB and c-Maf chromosomal translocations result in multiple myelomas. bZIP factors act in networks of homo and heterodimers in the regulation of a diverse set of cellular processes. The bZIP structural motif contains a basic region and a leucine zipper, composed of alpha helices with leucine residues 7 amino acids apart, which stabilize dimerization with a parallel leucine zipper domain. Dimerization of leucine zippers creates a pair of the adjacent basic regions that bind DNA and undergo conformational change. Dimerization occurs in a specific and predictable manner resulting in hundreds of dimers having unique effects on transcription.
Jiyao W et al.(2023). "The conserved domain database in 2023.",