Standard Lemma guide

helix-loop-helix

noun · 1 senses · updated from the 2026-07-25 local source snapshot

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1

noun

Meaning 1

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.

Definition source: English Wiktionary via Wiktextract

Topics: biochemistry, biology, chemistry, genetics, medicine, microbiology, natural-sciences, physical-sciences, sciences

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Meaning relationships

Synonyms: none provided

Antonyms: none provided

History

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.