Class A G protein-coupled receptor sodium allosteric site (GPCR Na+ site) (GPCR Na+ site)

The Class A G protein-coupled receptor (GPCR) sodium allosteric site is a highly conserved pocket located within the transmembrane bundle of most rhodopsin-like GPCRs (Katritch et al., 2014, Trends in Biochem Sci). This site is typically centered around a conserved aspartate residue at position 2.50 (Asp 2.50) and coordinates a sodium ion, which acts as a natural negative allosteric modulator by stabilizing the inactive conformation of the receptor (Liu et al., 2012, Science). Because this site is distinct from the orthosteric ligand-binding pocket, it offers a unique opportunity for the development of allosteric modulators that can fine-tune receptor signaling with high subtype selectivity (Fenalti et al., 2014, Nature). Drugs targeting this site, such as amiloride and its derivatives, can alter the affinity and efficacy of endogenous agonists, providing a rheostat effect rather than a simple on/off switch (Massink et al., 2015, Mol Pharmacol). This site is implicated in a wide range of physiological processes and diseases, including pain management via opioid receptors and cardiovascular regulation via adrenergic receptors (White et al., 2018, Chem Rev). However, the high conservation of the site across the Class A family poses a significant challenge for achieving drug specificity and avoiding off-target effects (Gao et al., 2014, Mol Pharmacol). Recent advances in structural biology have enabled the visualization of this site in various states, facilitating the rational design of site-specific ligands (Zheng et al., 2017, Chem Soc Rev). Targeting the sodium pocket is particularly relevant for receptors where orthosteric ligands lack sufficient selectivity or produce undesirable side effects (Strachan et al., 2014, Adv Pharmacol).

Other names

Conserved sodium binding pocketAsp2.50 allosteric siteSodium-binding site of Class A GPCRsNa+ pocket

Negative allosteric modulation of agonist binding and signaling by stabilizing the inactive receptor conformation through coordination with the conserved Asp2.50 residue.