title: The helix-loop-helix domain: a common motif for bristles, muscles and sex.
abstract: Three apparently unrelated developmental processes--mammalian myogenesis, the choice of neural fate and sex determination in Drosophila--are controlled by a common mechanism. Most of the genes governing these processes encode transcriptional factors that contain the helix-loop-helix (HLH) motif. This domain mediates the formation of homo- or heterodimers that specifically bind to DNA through a conserved basic region adjacent to the HLH motif. Dimers differ in their affinity for DNA and in their ability to activate transcription from HLH binding-site containing promoters. In addition, the activity of HLH proteins is inhibited by dimerization with another class of HLH proteins that lack a basic domain entirely or have an altered one. These structural properties provide a molecular mechanism to explain the synergistic and antagonistic functional relations among the HLH encoding genes that control several developmental pathways.
authors.affiliation: Centro de Biología Molecular, CSIC-UAM, Madrid, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Garrell
authors.forename: S
authors.initials: S
authors.lastname: Campuzano
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004330:Drosophila / Q000235:genetics; D005260:Female; D008297:Male; D008322:Mammals / Q000235:genetics; D008961:Models, Structural; D008969:Molecular Sequence Data; D009132:Muscles / Q000502:physiology*; D011487:Protein Conformation; D012689:Sequence Homology, Nucleic Acid; D012732:Sex Determination Analysis; D014157:Transcription Factors / Q000235:genetics*
chemical_list: D014157:Transcription Factors