title: Antagonist profile and molecular dynamic simulation of a Drosophila melanogaster muscarinic acetylcholine receptor.
abstract: A stably-transfected, Drosophila cell line (S2-DMl-1) expressing the Drosophila DMl muscarinic acetylcholine receptor (mAChR) exhibits high-affinity, saturable, specific binding of the radiolabelled muscarinic antagonist [3H]-N-methyl scopolamine ([3H]-NMS) with an equilibrium dissociation constant (Kd) of 0.67 +/- 0.02 and a Bmax of 1.53 +/- 0.3 pmol/mg protein. Displacement of [3H]-NMS by mAChR antagonists results in the pharmacological profile: 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP) > hexahydrosiladifenidol > p-fluorohexahydrosiladifenidol > nitrocaramiphen > pirenzepine > methoctramine > AFDX-116. This antagonist profile most closely resembles that of the vertebrate M3 mAChR subtype. In this study, however, we have demonstrated that the antagonist profile of DM1 is distinct from those of vertebrate mAChR subtypes. Molecular dynamic simulations of the Drosophila muscarinic receptor are presented in the free, carbamylcholine-bound and NMS-bound forms. Theoretical, quantitative structure-activity relationship models have been developed; a good correlation is observed between the interaction energies of the minimized ligand-receptor complexes and the pharmacological affinities of the antagonists tested.
authors.affiliation: Babraham Institute Laboratory of Molecular Signalling, Department of Zoology, University of Cambridge, UK.
authors.forename: C M
authors.initials: CM
authors.lastname: Reaper
authors.forename: F
authors.initials: F
authors.lastname: Fanelli
authors.forename: S D
authors.initials: SD
authors.lastname: Buckingham
authors.forename: N S
authors.initials: NS
authors.lastname: Millar
authors.forename: D B
authors.initials: DB
authors.lastname: Sattelle
mesh_terms: D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D004331:Drosophila melanogaster / Q000378:metabolism*; D018727:Muscarinic Antagonists / Q000737:chemistry / Q000494:pharmacology*; D011869:Radioligand Assay; D011976:Receptors, Muscarinic / Q000737:chemistry / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014162:Transfection
chemical_list: D018727:Muscarinic Antagonists; D011976:Receptors, Muscarinic