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The Action of a Negative Allosteric Modulator at the Dopamine D

Christopher J Draper-Joyce, Ravi Kumar Verma, Mayako Michino, Jeremy Shonberg, Anitha Kopinathan, Carmen Klein Herenbrink, Peter J Scammells, Ben Capuano, Ara M Abramyan, David M Thal, Jonathan A Javitch, etc.

Sci Rep. 2018 Jan 19;8(1):1208.

PMID: 29352161

Abstract:

Sodium ions (Na+) allosterically modulate the binding of orthosteric agonists and antagonists to many class A G protein-coupled receptors, including the dopamine D2 receptor (D2R). Experimental and computational evidences have revealed that this effect is mediated by the binding of Na+ to a conserved site located beneath the orthosteric binding site (OBS). SB269652 acts as a negative allosteric modulator (NAM) of the D2R that adopts an extended bitopic pose, in which the tetrahydroisoquinoline moiety interacts with the OBS and the indole-2-carboxamide moiety occupies a secondary binding pocket (SBP). In this study, we find that the presence of a Na+ within the conserved Na+-binding pocket is required for the action of SB269652. Using fragments of SB269652 and novel full-length analogues, we show that Na+ is required for the high affinity binding of the tetrahydroisoquinoline moiety within the OBS, and that the interaction of the indole-2-carboxamide moiety with the SBP determines the degree of Na+-sensitivity. Thus, we extend our understanding of the mode of action of this novel class of NAM by showing it acts synergistically with Na+ to modulate the binding of orthosteric ligands at the D2R, providing opportunities for fine-tuning of modulatory effects in future allosteric drug design efforts.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
AP215802156 SB269652 SB269652 215802-15-6 Price
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