page_title: Helix-turn-helix
hierarchical_section_title: Helix-turn-helix
caption_attribution_description: By Richard Wheeler (Zephyris) 2007. Lambda repressor protein bound to a lambda operator DNA sequence. From .
context_page_description: In proteins, the helix-turn-helix is a major structural motif capable of binding DNA. Each monomer incorporates two α helices, joined by a short strand of amino acids, that bind to the major groove of DNA. The HTH motif occurs in many proteins that regulate gene expression. It should not be confused with the helix-loop-helix motif.
context_section_description: In proteins, the helix-turn-helix (HTH) is a major structural motif capable of binding DNA. Each monomer incorporates two α helices, joined by a short strand of amino acids, that bind to the major groove of DNA. The HTH motif occurs in many proteins that regulate gene expression. It should not be confused with the helix-loop-helix motif.
caption: The λ repressor of bacteriophage lambda employs two helix-turn-helix motifs (left; green) to bind DNA (right; blue and red). The λ repressor protein in this image is a dimer
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