Maf transcription factors form a distinct family of the basic leucine zipper (bZip) transcription factors. The Maf family is divided into two subclasses, large Mafs (c-maf, mafB, and mafA/L-maf, nrl) and small Mafs (MafF, MafK and MafG). Both subclasses contain leucine-zipper motifs, which allow homodimerisation as well as heterodimerisation with a variety of other bZip proteins. In contrast to the small Mafs, the large Maf proteins contain a transactivator domain in their amino terminus.MafB plays critical roles in a variety of cellular differentiation processes, including in kidney podocytes [], macrophages [, ], and pancreatic islet alpha and beta-cells, which are responsible for the production of the hormones glucagon and insulin respectively. MafB is also expressed in alpha-cells in adult pancreas and is important for their function [, , , ].Mutations in Maf gene cause multicentric carpotarsal osteolysis syndrome (MCTO), which is a rare skeletal disorder, usually presenting in early childhood with a clinical picture mimicking juvenile rheumatoid arthritis [].
MafB constitutes a family of secreted toxins in pathogenic Neisseria species, probably involved in interbacterial competition []. Genes immediately downstream of mafB encode a specific immunity protein (MafI). MafB proteins exhibit a signal peptide sequence, a N-terminal conserved domain and a C-terminal variable region. Toxic domains identified at the C terminus include , , , and .The genus Neisseria includes both commensal and pathogenic species. The pathogenic neisseriae are a small group of virulent bacteria that initiate infection at the human host mucosal membranes []. Neisseria gonorrhoeae is passed through sexual transmission and can cause renal failure in extreme cases. The more extreme Neisseria meningitidis is a usually commensal nasopharynx microbe that causes meningococcemia and acute bacterial meningitis, especially in young children and teenagers [].
