V-Maf Musculoaponeurotic Fibrosarcoma Oncogene Homolog K (MAFK)

The developmentally regulated expression of the globin genes depends on upstream regulatory elements termed locus control regions (LCRs). LCRs are associated with powerful enhancer activity that is mediated by the transcription factor NFE2 (nuclear factor erythroid-2). NFE2 recognition sites are also present in the gene promoters of 2 heme biosynthetic enzymes, porphobilinogen deaminase (PBGD) and ferrochelatase (FECH). NFE2 DNA-binding activity consists of a heterodimer containing an 18-kD Maf protein (MafF, MafG or MafK) and p45. Both subunits are members of the activator protein-1 superfamily of basic leucine zipper (bZIP) proteins. Maf homodimers suppress transcription at NFE2 sites.