helix-loop-helix

== English == === Etymology === From helix + loop + helix. The term got its name from its distinct physical geometry; two alpha helices separated and connected by a flexible chain of amino acids known as a "loop", allowing the helices to pack together tightly. === Noun === helix-loop-helix (plural helix-loop-helices, abbreviation HLH) (biochemistry, genetics) A structural motif where two alpha helices are connected by a highly flexible amino acid loop, allowing the helices to pack together. Usually requires forming a dimer with another HLH protein before binding DNA. ==== Related terms ==== === Further reading === Sequence motif on Wikipedia.Wikipedia Structural motif on Wikipedia.Wikipedia Protein domain on Wikipedia.Wikipedia Transcription factor on Wikipedia.Wikipedia Myc on Wikipedia.Wikipedia