Basic leucine zipper (bZIP) domain of small 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 small Mafs (MafF, MafK, and MafG) do not contain a transactivation domain but do harbor the anxillary DNA-binding domain and a C-terminal bZIP domain. They form dimers with cap'n'collar (CNC) proteins that harbor transactivation domains, and they act either as activators or repressors depending on their dimerization partner. CNC transcription factors include NFE2 (nuclear factor, erythroid-derived 2) and similar proteins NFE2L1 (NFE2-like 1), NFE2L2, and NFE2L3, as well as BACH1 and BACH2. Small Mafs play roles in stress response and detoxification pathways. They also regulate the expression of betaA-globin and other genes activated during erythropoiesis. They have been implicated in various diseases such as diabetes, neurological diseases, thrombocytopenia and cancer. Triple deletion of the three small Mafs is embryonically lethal. 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.",