Ligand Selectivity of D₂Dopamine Receptors Is Modulated by Changes in Local Dynamics Produced by Sodium Binding

Abstract

We have uncovered a significant allosteric response of the D 2 dopamine receptor to physiologically relevant concentrations of sodium (140 mM Our findings demonstrate how key interactions can be modulated by occupancy at an allosteric site and are consistent with a mechanism in which sodium binding enhances the affinity of selected ligands through dynamic changes that increase accessibility of substituted benzamides and 1,4-DAP ligands to the orthosteric site and accessibility of 1,4-DAPs to V2.61(91)F.Sodium ions have been shown to modulate dopamine receptors, and allosteric modulation by sodium ions has been shown to drive the conformational equilibrium of heterotrimeric G protein-coupled receptors (GPCRs) toward an agonist low-affinity state (for review, see Schetz, 2005). In dopamine receptors, like in other heterotrimeric GPCRs, the highly conserved and negatively charged aspartic acid at position 2.50 (the generic numbering system is defined in Ballesteros and Weinstein, 1995) has been identified as a sodium interaction site. For example, charge-neutralizing mutations in the D 2 or the D 4 receptor [e.g., D2.50(80)N or D2.50(80)A] make them sodium-insensitive, whereas a charge-sparing mutation [e.g., D2.50(80)E] retains much of the sodium sensitivity (Neve et al

Endogenous Allosteric Modulators of G Protein–Coupled Receptors

“…Subsequent studies suggested that the effect of Na 1 likely involves modulation of the conformational state of the receptor (Simon and Groth, 1975), and that the binding of certain antagonists can actually be potentiated by the ion (Appelmans et al, 1986), one of the key characteristics exploited in the biochemical identification and validation of inverse agonism (Costa and Herz, 1989). These observations were soon extended to numerous other class A GPCRs, including those for biogenic amines, nucleosides, peptides, and lipids (Ericksen et al, 2009;Liu et al, 2012;Katritch et al, 2013); Fig. 4A shows an example of opposing effects of Na 1 on the binding of an agonist (quinpirole) and inverse agonist (epidepride) at the dopamine D 2 receptor (Neve, 1991), which is consistent with the expectations of behavior within a two-state receptor model (Christopoulos, 2014).…”

The HIV Antiretroviral Drug Efavirenz has LSD-Like Properties

“…Host cell lines lacking the receptor subtypes of interest were used to stably express individual cloned receptors as described by us previously (Ericksen et al, 2009). The human embryonic kidney (HEK293) cell type was used for the expression of the following receptors: cloned rat dopamine D 2 and D 4 receptors, human a 2C receptor, and human serotonin 5-HT 1A , 5-HT 2A , and 5-HT 2C receptors.…”

“…CHO, Att20, and CHO-K1 cells were host cell types for expressing cloned human dopamine D 1 , dopamine D 3 , and human histamine H 1 receptors, respectively, and the MCF-7 cell type was the host for expressing the cloned human Sigma 1 receptor. The expression level of the different receptor subtypes in individual clonal lines was determined by radioligand saturation isotherm binding utilizing rapid filtration techniques and cell membrane preparation as described previously (Ericksen et al, 2009). Permeabilized platelets from New Zealand albino rabbit was the source of VMAT2 (Cesura et al, 1990).…”

Ring Substituents on Substituted Benzamide Ligands Indirectly Mediate Interactions with Position 7.39 of Transmembrane Helix 7 of the D4 Dopamine Receptor

“…With the exceptions of N- [2-[2-hydroxy-3-[4-(4-hydroxy-3-methoxyphenyl) Membrane Preparation. Wild-type and mutant rat D4 dopamine receptors were stably expressed in HEK239 cells by using the same methodology as described previously (Kortagere et al, 2004;Ericksen et al, 2009). In brief, plasmid DNA containing the receptor and a resistance gene for G418 were transfected by CaPO 4 precipitation into a low confluence of HEK293 cells.…”