title: Functional probes of drug-receptor interactions implicated by structural studies: Cys-loop receptors provide a fertile testing ground.
abstract: Structures of integral membrane receptors provide valuable models for drug-receptor interactions across many important classes of drug targets and have become much more widely available in recent years. However, it remains to be determined to what extent these images are relevant to human receptors in their biological context and how subtle issues such as subtype selectivity can be informed by them. The high precision structural modifications enabled by unnatural amino acid mutagenesis on mammalian receptors expressed in vertebrate cells allow detailed tests of predictions from structural studies. Using the Cys-loop superfamily of ligand-gated ion channels, we show that functional studies lead to detailed binding models that, at times, are significantly at odds with the structural studies on related invertebrate proteins. Importantly, broad variations in binding interactions are seen for very closely related receptor subtypes and for varying drugs at a given binding site. These studies highlight the essential interplay between structural studies and functional studies that can guide efforts to develop new pharmaceuticals.
authors.affiliation: Division of Chemistry and Chemical Engineering, California Institute of Technology , Pasadena, California 91125, United States.
authors.forename: Ethan B
authors.initials: EB
authors.lastname: Van Arnam
authors.forename: Dennis A
authors.initials: DA
authors.lastname: Dougherty
mesh_terms: D000596:Amino Acids / Q000235:genetics; D000818:Animals; D001665:Binding Sites; D018755:GABA Agonists / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D015640:Ion Channel Gating; D008024:Ligands; D009154:Mutation; D018722:Nicotinic Agonists / Q000737:chemistry / Q000494:pharmacology; D004364:Pharmaceutical Preparations / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018079:Receptors, GABA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018009:Receptors, Glycine / Q000819:agonists / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011978:Receptors, Nicotinic / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D044406:Receptors, Serotonin, 5-HT3 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D058827:Serotonin 5-HT3 Receptor Agonists / Q000737:chemistry / Q000494:pharmacology
chemical_list: D000596:Amino Acids; D018755:GABA Agonists; D008024:Ligands; D018722:Nicotinic Agonists; D004364:Pharmaceutical Preparations; D021122:Protein Subunits; D011956:Receptors, Cell Surface; D018079:Receptors, GABA; D018009:Receptors, Glycine; D011978:Receptors, Nicotinic; D044406:Receptors, Serotonin, 5-HT3; D058827:Serotonin 5-HT3 Receptor Agonists