Figure 2

Amino acid substitutions in the zinc knuckle domain in cod zkY and its autosomal copies. (A) Sequence alignment of the zinc knuckle domain (boxed) and flanking regions in cod zkY and the eight autosomal protein variants. The characteristic Cys-Cys-His-Cys residues of the zinc knuckle are arrowed, substituted amino acids are indicated by colors and correspond to the labelled positions 435, 437, and 443 in (B-D). Repeated segments adjacent to the zinc knuckle are shaded. (B–D) Modeled structure of the three different zinc knuckle domains of cod zkY and the autosomal proteins. The Zn²⁺ ion is displayed together with the oligonucleotide d(ACGCC) template (see Methods). (B) Met443 variant of zkY, zk1, zk2, (C) Ile443 variant of zk3-zk7, (D) Lys435-Arg437-Gln443 variant of zk8. Hydrogen bonds are indicated by dotted green lines, Pi-donor hydrogen bonds in light blue, hydrophobic interactions by dotted magenta lines, and electrostatic bonds by dotted orange lines.