The Role of Water and Sodium Ions in the Activation of the μ‐Opioid Receptor

Dual effect of sodium ions: The activation of G-protein-coupled receptors depends on the presence of water molecules inside the receptor and also on allosteric interactions. The binding of sodium ions to the allosteric site of the μ opioid receptor was studied by microsecond molecular dynamics simulations and their seemingly contradictory roles in preventing ligand binding and facilitating receptor activation were explained.