DNA binding domains called as basic domains rich in basic amino acids that was happen in transcription factors in combination with zipper helix-loop-helix or leucine (HLH) dimerization domains. The combination of basic domain and dimerization domain provide these proteins their names of basic leucine zipper proteins (bZIP) or basic HLH proteins, respectively. In every case the dimerization means which two basic domains one from every monomer interact with the goal DNA.