Helix-turn-helix, zinc-finger, and leucine-zipper motifs for eukaryotic transcriptional regulatory proteins.

Four distinct structural motifs have been proposed for the DNA-binding domains of eukaryotic transcriptional regulatory proteins; the helix-turn-helix, two kinds of zinc finger, and the leucine zipper. Within each structural motif, there are often families of related proteins that recognize similar DNA sequences and are conserved throughout the eukaryotic kingdom. However, the processes of transcriptional activation and repression appear to be independent of the specific type of protein-DNA interaction.