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Figure 3. C2H2 zinc finger motif. (A) The C2H2 zinc finger motif (2 Cys and 2 His residues bonded tetrahedrally to a Zn ion) consists of a short antiparallel ß-sheet formed by two ß-strands and hairpin turn, followed by an 
-helix (adapted from Lee et al., 1989). (B) Co-crystal structure of Zif268/DNA as determined by Pavletich and Pabo (1993). Note the -helices wrapped around the major groove of the DNA. N denotes the N-terminus. (C) ß-strands (arrows) and hairpin turn (curved line), followed by an -helix (blue helix) that usually fits into the major groove of the target DNA. Conserved amino acids are underlined. Amino acids (red) at positions –1, +3, and +6 relative to the beginning of the -helix are primarily responsible for interactions with DNA.
