Homeobox (IPR001356) encodes transcriptional regulators that consist of homeodomains and execute distinct genetic programs along the animal body's anterior-posterior axis. This domain binds DNA through a helix-turn-helix (HTH) structure. Two alpha helices, in close proximity to DNA and connected by a brief turn, distinguish the HTH motif. The sequence and structure of this motif are strikingly similar in a diverse array of DNA-binding proteins, including cro and repressor proteins, homeobox proteins, and others.