The role of a sodium ion binding site in the allosteric modulation of the A(2A) adenosine G protein-coupled receptor

Structure. 2013 Dec 3;21(12):2175-85. doi: 10.1016/j.str.2013.09.020. Epub 2013 Nov 7.


The function of G protein-coupled receptors (GPCRs) can be modulated by a number of endogenous allosteric molecules. In this study, we used molecular dynamics, radioligand binding, and thermostability experiments to elucidate the role of the recently discovered sodium ion binding site in the allosteric modulation of the human A(2A) adenosine receptor, conserved among class A GPCRs. While the binding of antagonists and sodium ions to the receptor was noncompetitive in nature, the binding of agonists and sodium ions appears to require mutually exclusive conformational states of the receptor. Amiloride analogs can also bind to the sodium binding pocket, showing distinct patterns of agonist and antagonist modulation. These findings suggest that physiological concentrations of sodium ions affect functionally relevant conformational states of GPCRs and can help to design novel synthetic allosteric modulators or bitopic ligands exploiting the sodium ion binding pocket.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine A2 Receptor Agonists / chemistry
  • Adenosine A2 Receptor Antagonists / chemistry
  • Allosteric Regulation
  • Allosteric Site
  • Amiloride / analogs & derivatives
  • Amiloride / chemistry
  • Amino Acid Sequence
  • Cations, Monovalent
  • HEK293 Cells
  • Hot Temperature
  • Humans
  • Molecular Dynamics Simulation
  • Molecular Sequence Data
  • Protein Conformation
  • Protein Stability
  • Radioligand Assay
  • Receptor, Adenosine A2A / chemistry
  • Receptor, Adenosine A2A / metabolism*
  • Sodium / chemistry
  • Sodium / metabolism*


  • Adenosine A2 Receptor Agonists
  • Adenosine A2 Receptor Antagonists
  • Cations, Monovalent
  • Receptor, Adenosine A2A
  • 5-(N,N-hexamethylene)amiloride
  • Amiloride
  • Sodium