helix-turn-helix

== English == === Etymology === From helix + turn + helix. The term got its name from its distinct physical geometry; two alpha helices separated by a short amino acid sequence connecting the helices, where one helix recognizes and binds to a specific sequence in DNA. === Noun === helix-turn-helix (usually uncountable, plural helix-turn-helices) (biochemistry, genetics) A structural motif where two alpha helices are joined by a short amino acid loop, frequently acting as a DNA binding site. ==== Related terms ==== === Further reading === Sequence motif on Wikipedia.Wikipedia Structural motif on Wikipedia.Wikipedia Protein domain on Wikipedia.Wikipedia