Class A G protein-coupled receptor conserved sodium allosteric site

The Class A G protein-coupled receptor (GPCR) conserved sodium allosteric site is a highly conserved pocket located within the seven-transmembrane helical bundle of the majority of Class A GPCRs (Katritch et al., 2014). Centered around the nearly invariant Aspartate residue at position 2.50 (D2.50), this site binds a hydrated sodium ion that acts as a negative allosteric modulator, stabilizing the inactive conformation of the receptor and reducing the affinity for agonists (Liu et al., 2012; Katritch et al., 2014). This site is critical for the regulation of signal transduction across a wide range of physiological processes, including neurotransmission and hormonal response (Massink et al., 2015). Because of its high conservation, the sodium binding pocket represents a unique target for the development of allosteric modulators that can fine-tune receptor activity (White et al., 2018). Drugs such as amiloride and its derivatives have been shown to bind this site, offering a template for novel therapeutic interventions in diseases like Parkinson's, chronic pain, and cardiovascular disorders (Katritch et al., 2014). However, the high physiological concentration of sodium and the site's ubiquity across hundreds of receptors present significant challenges for achieving drug potency and selectivity (Massink et al., 2015).

Other names

D2.50 allosteric siteSodium ion binding pocketGPCR sodium pocketAllosteric sodium siteNa+ binding site

Binding of sodium ions or synthetic ligands to the site stabilizes the inactive (R) state of the receptor, acting as a negative allosteric modulator (NAM) that decreases agonist affinity and signaling efficacy (Liu et al., 2012; Katritch et al., 2014).