Since they lack a putative transactivation domain, the small Mafs behave as transcriptional repressors when they dimerize among themselves (PubMed:11154691). However, they seem to serve as transcriptional activators by dimerizing with other (usually larger) basic-zipper proteins, such as NFE2, NFE2L1 and NFE2L2, and recruiting them to specific DNA-binding sites (PubMed:11154691, PubMed:8932385, PubMed:9421508). Small Maf proteins heterodimerize with Fos and may act as competitive repressors of the NFE2L2 transcription factor (PubMed:11154691). Transcription factor, component of erythroid-specific transcription factor NFE2L2 (PubMed:11154691). Activates globin gene expression when associated with NFE2L2 (PubMed:11154691). May be involved in signal transduction of extracellular H(+) (By similarity).
