Basic helix–loop–helix transcription factor (bHLH)

The basic helix–loop–helix transcription factor is a class of dimeric transcriptional regulators defined by a protein motif with two α-helices separated by a loop, including a run of basic amino acids critical for DNA binding. Members of this family regulate gene transcription through binding to E-box DNA motifs, and they participate in the control of essential biological processes such as development, cell proliferation, tissue specification, metabolism, circadian rhythms, and stress responses. Functionality is often mediated via homo- or hetero-dimerization, and further specified by associated domains such as leucine-zippers (bHLHZ) or PAS domains (bHLH-PAS). While the family as a whole is not a specific drug target, individual bHLH proteins (e.g., c-Myc, HIF-1α, AHR, CLOCK) are key regulatory nodes and validated therapeutic targets implicated in various diseases, especially cancer and developmental disorders.

Other names

bHLH transcription factorhelix–loop–lix (HLH) proteinbasic HLH protein

(for drugs targeting individual bHLH proteins) - Inhibit DNA-binding activity - Disrupt dimerization - Block protein expression or stability - Modulate ligand-dependent activation