Small heterodimeric partner

As mentioned above, the bZIP proteins function as dimers in order to bind to DNA. Presently, there is no conclusive evidence to indicate whether Nrf2 may activate gene expression as a homodimer or whether it is obligated to form heterodimeric complexes. Because p45 NF-E2, the first family member of these proteins, was found to dimerize with MafK in order to bind DNA and activate transcription (56), it was hypothesized that small Maf proteins may represent a partner for Nrf2 in effecting transcriptional activation (52). 

---