title: Considerations on the structural evidence of a ligand-binding function of ultraspiracle, an insect homolog of vertebrate RXR.
abstract: This analysis considers the structural evidence of a ligand-binding function of the nuclear receptor ultraspiracle (USP). The positions and nature of residues in the ligand-binding domain of USP from six higher insects is evaluated in comparison to the function of conserved residues vertebrate receptors that have been co-crystallized with ligand. USP appears to conserve residues that in vertebrate receptors (1) form the hydrophobic ligand-binding pocket, (2) contact oxygen-containing moieties on ligands, such as hydroxyl, keto and carboxyl groups, and (3) in response to ligand-binding conformationally change to form a multi-helix hydrophobic groove for recruitment of transcriptional co-activators. These structural features are consistent with the recent report that USP can bind the epoxymethylfarnesoates (juvenile hormones) and thereupon is induced to change conformation.
authors.affiliation: School of Biological Sciences, University of Kentucky, Lexington, KY 40506, USA. gjones@pop.uky.edu
authors.forename: G
authors.initials: G
authors.lastname: Jones
authors.forename: D
authors.initials: D
authors.lastname: Jones
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D029721:Drosophila Proteins; D006801:Humans; D007313:Insecta; D008024:Ligands; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D018168:Receptors, Retinoic Acid / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D011987:Receptors, Steroid / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D047488:Retinoid X Receptors; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D014714:Vertebrates
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D008024:Ligands; D018168:Receptors, Retinoic Acid; D011987:Receptors, Steroid; D047488:Retinoid X Receptors; D015534:Trans-Activators; D014157:Transcription Factors; C066030:USP protein, Drosophila