 Target-site overlap may also affect the selection of zinc fingers during by display, in cases where amino acids on a non-randomised finger, and the bases of its associated subsite, influence the binding of residues on the adjacent finger which contains the randomised residues.Indeed, attempts to derive zinc finger proteins targeting the 5'-(A/T)NN-3' family of sequences by site-directed mutagenesis of finger two of the C7 protein were unsuccessful due to the Asp2 of the third finger of said protein.The extent to which target-site overlap occurs is largely unknown, with a variety of amino acids having shown involvement in such interactions.