GAL4 binding sites. The yeast transcription factor GAL4 binds to DNA sequences of the form 5′-CGG(N)11CCG-3′. Two zinc-based domains are present in the DNA-binding region of this protein. Notice that these domains contact the 5′-CGG-35′ sequences, leaving the center of the site uncontacted.
[Drawn from 1D66.pdb.]