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Effect of Multiple Serine/Alanine Mutations in the Transmembrane Spanning Region V of the D 2 Dopamine Receptor on Ligand Binding
Author(s) -
Coley Clare,
Woodward Robert,
Johansson Anette M.,
Strange Philip G.,
Naylor Louise H.
Publication year - 2000
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.2000.0740358.x
Subject(s) - dopamine receptor d2 , alanine , chemistry , mutant , receptor , spiperone , serine , transmembrane domain , dopamine receptor , dopamine receptor d1 , dopamine , ligand (biochemistry) , biochemistry , stereochemistry , biology , amino acid , enzyme , gene , endocrinology
Three conserved serine residues (Ser 193 , Ser 194 , and Ser 197 ) in transmembrane spanning region (TM) V of the D 2 dopamine receptor have been mutated to alanine, individually and in combination, to explore their role in ligand binding and G protein coupling. The multiple Ser → Ala mutations had no effect on the binding of most antagonists tested, including [ 3 H]spiperone, suggesting that the multiple mutations did not affect the overall conformation of the receptor protein. Double or triple mutants containing an Ala 197 mutation showed a decrease in affinity for domperidone, whereas Ala 193 mutants showed an increased affinity for a substituted benzamide, remoxipride. However, dopamine showed large decreases in affinity (>20‐fold) for each multiple mutant receptor containing the Ser 193 Ala mutation, and the high‐affinity (coupled) state of the receptor (in the absence of GTP) could not be detected for any of the multiple mutants. A series of monohydroxylated phenylethylamines and aminotetralins was tested for their binding to the native and multiple mutant D 2 dopamine receptors. The results obtained suggest that Ser 193 interacts with the hydroxyl of S ‐5‐hydroxy‐2‐dipropylaminotetralin (OH‐DPAT) and Ser 197 with the hydroxyl of R ‐5‐OH‐DPAT. We predict that Ser 193 interacts with the hydroxyl of R ‐7‐OH‐DPAT and the 3‐hydroxyl ( m ‐hydroxyl) of dopamine. Therefore, the conserved serine residues in TMV of the D 2 dopamine receptor are involved in hydrogen bonding interactions with selected antagonists and most agonists tested and also enable agonists to stabilise receptor‐G protein coupling.