Helix-Loop-Helix Motifs

**Definition:** Recurring supersecondary structures characterized by 20 amino acids folding into two alpha helices connected by a non-helical loop segment. They are found in many sequence-specific DNA-BINDING PROTEINS and in CALCIUM-BINDING PROTEINS.

**Tree numbers:** - G02.111.570.820.709.275.500.360

**Synonyms:** - HLH Motifs - Motifs, Helix-Loop-Helix - Helix-Loop-Helix Motif - Helix-Loop-Helix Domain - Helix-Loop-Helix Domains