title: Dopamine D1 receptor-agonist interactions: A mutagenesis and homology modeling study.
abstract: The dopamine D1 receptor is a G protein-coupled receptor that regulates intracellular signaling via agonist activation. Although the number of solved GPCR X-ray structures has been steadily increasing, still no structure of the D1 receptor exists. We have used site-directed mutagenesis of 12 orthosteric vicinity residues of possible importance to G protein-coupled activation to examine the function of prototypical orthosteric D1 agonists and partial agonists. We find that residues from four different regions of the D1 receptor make significant contributions to agonist function. All compounds studied, which are catechol-amines, are found to interact with the previously identified residues: the conserved D103(3.32), as well as the trans-membrane V serine residues. Additional key interactions are found for trans-membrane VI residues F288(6.51), F289(6.52) and N292(6.55), as well as the extra-cellular loop residue L190(ECL2). Molecular dynamics simulations of a D1 homology model have been used to help put the ligand-residue interactions into context. Finally, we considered the rescaling of fold-shift data as a method to account for the change in the size of the mutated side-chain and found that this rescaling helps to relate the calculated ligand-residue energies with observed experimental fold-shifts.
authors.affiliation: Pfizer Worldwide Research and Development, 610 Main Street, Cambridge, MA 02139, United States. Electronic address: scot.mente@pfizer.com.
authors.forename: Scot
authors.initials: S
authors.lastname: Mente
authors.affiliation: Pfizer Worldwide Research and Development, 610 Main Street, Cambridge, MA 02139, United States.
authors.forename: Edward
authors.initials: E
authors.lastname: Guilmette
authors.affiliation: Pfizer Worldwide Research and Development, 610 Main Street, Cambridge, MA 02139, United States.
authors.forename: Michelle
authors.initials: M
authors.lastname: Salafia
authors.affiliation: Pfizer Worldwide Research and Development, 610 Main Street, Cambridge, MA 02139, United States.
authors.forename: David
authors.initials: D
authors.lastname: Gray
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D018491:Dopamine Agonists / Q000494:pharmacology*; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis; D051381:Rats; D017447:Receptors, Dopamine D1 / Q000819:agonists* / Q000737:chemistry
chemical_list: D018491:Dopamine Agonists; D017447:Receptors, Dopamine D1
keywords: Dopamine; Dopamine receptors; Homology model; Molecular dynamics; Mutation