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Mutation W284L of the human delta opioid receptor reveals agonist specific receptor conformations for G protein

Y Hosohata1, E V Varga, D Stropova

  • 1Department of Pharmacology, The University of Arizona, Tucson 85724, USA.

Life Sciences
|May 19, 2001
PubMed

Insights

This study reveals how mutations in the human delta opioid receptor (hDOR) affect the binding and activity of different opioid agonists. Understanding these interactions is key to developing targeted pain relief medications.

Area of Science:

  • Pharmacology
  • Molecular Biology
  • Biochemistry

Background:

  • The delta opioid receptor (DOR) plays a crucial role in pain modulation and other physiological processes.
  • Understanding the structure-activity relationships of DOR agonists is essential for developing selective therapeutics.
  • Previous studies have explored various mutations affecting receptor function, but specific conformational changes remain to be elucidated.

Purpose of the Study:

  • To investigate the impact of the W284L mutation in the human delta opioid receptor (hDOR) on the binding affinities and intrinsic activities of various delta opioid agonists.
  • To determine if different chemical classes of delta opioid agonists utilize distinct receptor conformations for G protein activation.

Main Methods:

  • Utilized a [35S]GTPgammaS binding assay to measure the intrinsic activities of delta opioid agonists.
  • Employed Chinese hamster ovary (CHO) cells stably expressing either wild-type hDOR (hDOR/CHO) or the W284L mutant hDOR (W284L/CHO).
  • Assessed agonist binding affinities in the presence and absence of sodium and guanine nucleotides.

Main Results:

  • The W284L mutation differentially affected agonist binding affinities and intrinsic activities, with SNC 80 showing reduced affinity but higher maximal stimulation.
  • Agonist binding affinities were more robustly regulated by sodium and guanine nucleotide in the W284L mutant compared to wild-type receptors.
  • Different chemical classes of delta opioid agonists exhibited distinct responses to the W284L mutation, suggesting class-specific conformational states.

Conclusions:

  • The W284L mutation in hDOR alters receptor function, impacting the affinity and efficacy of various delta opioid agonists.
  • The findings support the hypothesis that delta opioid agonists of different chemical classes adopt specific conformations to activate G proteins.
  • This research provides valuable insights into the conformational dynamics of the delta opioid receptor and its interactions with diverse agonists.

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