Since they lack a putative transactivation domain, the small Mafs behave as transcriptional repressors when they dimerize among themselves (PubMed:8932385). However, they seem to serve as transcriptional activators by dimerizing with other (usually larger) basic-zipper proteins, such as NFE2L1/NRF1, and recruiting them to specific DNA-binding sites. Interacts with the upstream promoter region of the oxytocin receptor gene (PubMed:8932385, PubMed:16549056). May be a transcriptional enhancer in the up-regulation of the oxytocin receptor gene at parturition (PubMed:10527846). Monomer and homo- or heterodimer. Interacts with MIP (PubMed:16549056). Forms high affinity heterodimers with members of the CNC-bZIP family such as NFE2L1/NRF1 (PubMed:8932385). Expressed in the term myometrium and kidney. By oxidative stress. Belongs to the bZIP family. Maf subfamily.