Dopamine D2 receptor dimer (D2R dimer)

The Dopamine D2 receptor dimer is a quaternary protein complex formed by the association of two Dopamine D2 receptor (D2R) protomers, which are members of the Class A G protein-coupled receptor (GPCR) family [1, 2]. While D2Rs were historically characterized as monomeric, they exist in a dynamic equilibrium with homodimeric and heterodimeric forms that exhibit distinct pharmacological and signaling properties [1, 4]. These dimers are primarily located in the striatum and other dopaminergic pathways, where they modulate essential biological functions such as motor control, reward processing, and cognitive stability [1, 5]. Pathological changes in the dimerization state, such as an increased D2R dimer-to-monomer ratio, have been linked to the etiology of schizophrenia and the mechanism of amphetamine sensitization [1, 6]. Pharmacological targeting of the D2R dimer represents a novel therapeutic strategy, particularly through the use of bivalent ligands that can bridge the two orthosteric binding sites of the complex [1, 3]. Such compounds, along with bitopic/dualsteric molecules like SB269,652, offer the potential for dimer-selective modulation, which may improve clinical efficacy and reduce the side-effect profile associated with traditional antipsychotics [1, 6]. Traditional D2R antagonists and agonists also interact with these dimeric assemblies, often exhibiting negative cooperativity where ligand binding at one protomer reduces the affinity at the second [2, 4]. Understanding the structural interface of the dimer, often involving transmembrane segments 4 and 5, remains a key area of research for developing next-generation neuropsychiatric treatments [1, 2].

Other names

DRD2 homodimerD2-D2 receptor complexD2R-D2R dimerDopamine D2 receptor homodimerD2R homomer

Negative allosteric modulation of the dimeric complex, orthosteric antagonism or agonism at individual protomers, bivalent binding to dual orthosteric sites, and allosteric crosstalk between protomers.