Answer:
5. Activator B dimerizes through its zinc finger motif
Explanation:
Leucine zipper proteins contain one leucine-rich repeat motif exclusively required for the dimerization of leucine-zipper proteins, and another motif with the ability to bind specific DNA sequences. Both leucine motifs form a coiled-coil region that mediates the dimerization by hydrophobic leucine zipper layers. These proteins are widely conserved and their family members can form both homodimers and heterodimers between proteins containing leucine zipper domains.