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Ligand with Two Modes of Interaction with the Dopamine D2 Receptor-An Induced-Fit Mechanism of Insurmountable Antagonism.


ABSTRACT: A solid understanding of the mechanisms governing ligand binding is crucial for rational design of therapeutics targeting the dopamine D2 receptor (D2R). Here, we use G protein-coupled inward rectifier potassium (GIRK) channel activation in Xenopus oocytes to measure the kinetics of D2R antagonism by a series of aripiprazole analogues, as well as the recovery of dopamine (DA) responsivity upon washout. The aripiprazole analogues comprise an orthosteric and a secondary pharmacophore and differ by the length of the saturated carbon linker joining these two pharmacophores. Two compounds containing 3- and 5-carbon linkers allowed for a similar extent of recovery from antagonism in the presence of 1 or 100 ?M DA (>25 and >90% of control, respectively), whereas recovery was less prominent (?20%) upon washout of the 4-carbon linker compound, SV-III-130, both with 1 and 100 ?M DA. Prolonging the coincubation time with SV-III-130 further diminished recovery. Curve-shift experiments were consistent with competition between SV-III-130 and DA. Two mutations in the secondary binding pocket (V91A and E95A) of D2R decreased antagonistic potency and increased recovery from SV-III-130 antagonism, whereas a third mutation (L94A) only increased recovery. Our results suggest that the secondary binding pocket influences recovery from inhibition by the studied aripiprazole analogues. We propose a mechanism, supported by in silico modeling, whereby SV-III-130 initially binds reversibly to the D2R, after which the drug-receptor complex undergoes a slow transition to a second ligand-bound state, which is dependent on secondary binding pocket integrity and irreversible during the time frame of our experiments.

SUBMITTER: Agren R 

PROVIDER: S-EPMC7553383 | biostudies-literature | 2020 Oct

REPOSITORIES: biostudies-literature

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Ligand with Two Modes of Interaction with the Dopamine D<sub>2</sub> Receptor-An Induced-Fit Mechanism of Insurmountable Antagonism.

Ågren Richard R   Zeberg Hugo H   Stępniewski Tomasz Maciej TM   Free R Benjamin RB   Reilly Sean W SW   Luedtke Robert R RR   Århem Peter P   Ciruela Francisco F   Sibley David R DR   Mach Robert H RH   Selent Jana J   Nilsson Johanna J   Sahlholm Kristoffer K  

ACS chemical neuroscience 20200915 19


A solid understanding of the mechanisms governing ligand binding is crucial for rational design of therapeutics targeting the dopamine D<sub>2</sub> receptor (D<sub>2</sub>R). Here, we use G protein-coupled inward rectifier potassium (GIRK) channel activation in <i>Xenopus</i> oocytes to measure the kinetics of D<sub>2</sub>R antagonism by a series of aripiprazole analogues, as well as the recovery of dopamine (DA) responsivity upon washout. The aripiprazole analogues comprise an orthosteric and  ...[more]

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