RGS4

RGS4 (Regulator of G-Protein Signaling 4) is a member of the R4 subfamily of regulator of G-protein signaling proteins and functions as a GTPase-activating protein that accelerates GTP hydrolysis on heterotrimeric Gα subunits, thereby terminating GPCR-mediated signal transduction and driving G proteins into their inactive GDP-bound state^[1][2]. Mechanistically, RGS4 negatively regulates signaling mediated by Gα_i, Gα_o, and Gα_q family members, placing it at a critical control point for neurotransmitter- and receptor-dependent cellular responses^[1][2]. In the central nervous system, RGS4 is broadly expressed and contributes to the modulation of neurotransmitter pathways, including dopamine, glutamate, and opioid signaling, processes that are highly relevant to neuronal activity and synaptic regulation^[3][4]. Disease-associated studies have identified altered RGS4 expression in schizophrenia, supporting its relevance to psychiatric disease mechanisms and cortical dysfunction^[5][6]. In experimental models of Parkinson’s disease, genetic deletion or pharmacological inhibition of RGS4 influences dopaminergic signaling and modifies behavioral and synaptic outcomes following dopamine depletion, highlighting its utility as a mechanistic target in movement-disorder research^[7][8]. Compared with related RGS family members, RGS4 belongs to the small R4 subgroup characterized by a conserved RGS domain and potent regulation of GPCR signaling through direct Gα-subunit interactions^[2]. For experimental applications, small-molecule RGS4 inhibitors such as CCG-203920 have been used to enhance GPCR-dependent signaling and investigate the contribution of RGS4 to opioid receptor and dopaminergic pathways in cellular and animal models^[8].