Best Sp1-DNA complex model and detailed interaction scheme. (A) The best Sp1-DNA complex model generated on the basis of two AIRs in each domain. (B) The interacting residues in zinc fingers 1, 2 and 3 are cyan, magenta and orange, respectively. The interacting DNA bases are salmon. The solid lines and dotted lines indicate the hydrogen bonds and non-bond contacts, respectively. The residues and bases used as AIRs for docking are marked with an asterisk.