| helix-loop-helix motifs | A group of 20-residue peptides characterised by two alpha helices separated by a non-helical segment. These recurring supersecondary structural patterns are found in many sequence-specific DNA-binding proteins. (12 Dec 1998) |
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| helix-turn-helix motifs | The first DNA-binding protein motif to be recognised. Helix-turn-helix motifs were originally identified in bacterial proteins but have since been found in hundreds of DNA-binding proteins from both eukaryotes and prokaryotes. They are constructed from two alpha helices connected by a short extended chain of amino acids, which constitute the "turn." the two helices are held at a fixed angle, primarily through interactions between the two helices. (12 Dec 1998) |