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A "locked-on," constitutively active mutant of the adenosine A1 receptor

Rianne A F de Ligt1, Scott A Rivkees, Anna Lorenzen

  • 1Division of Medicinal Chemistry, Leiden/Amsterdam Center for Drug Research, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands.

European Journal of Pharmacology
|March 3, 2005
PubMed

Insights

Researchers discovered constitutively active mutant (CAM) adenosine A1 receptors, with Gly14Thr exhibiting a unique "locked-on" state unresponsive to agonists or inverse agonists, advancing our understanding of receptor function.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Pharmacology

Background:

  • The adenosine A1 receptor (A1R) is a G protein-coupled receptor involved in various physiological processes.
  • Understanding A1R function and regulation is crucial for developing targeted therapeutics.

Purpose of the Study:

  • To investigate the functional consequences of specific mutations at position 14 of the human A1R.
  • To characterize constitutively active mutant (CAM) A1Rs and their unique properties.

Main Methods:

  • Radioligand binding assays to characterize receptor-ligand interactions.
  • GTPgammaS binding assays to assess G protein activation.
  • cAMP production assays in intact cells to measure receptor function.

Main Results:

  • Mutations at A1R position 14 (Gly14Ala, Gly14Leu, Gly14Thr) resulted in constitutively active receptors (CAMs).
  • The wild-type and Gly14Thr mutant receptors showed differential allosteric modulation by sodium ions and PD81,723.
  • The Gly14Thr mutant exhibited a "locked-on" phenotype, with basal activity unaffected by agonists or inverse agonists in both GTPgammaS and cAMP assays.

Conclusions:

  • This study provides the first evidence of CAM A1Rs.
  • The Gly14Thr mutant displays a unique, non-modifiable "locked-on" state, offering insights into A1R activation mechanisms.
  • These findings contribute to a deeper understanding of A1R signaling and allosteric modulation.

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