Dopamine- and cAMP-regulated neuronal phosphoprotein 32 kDa (DARPP-32)

Dopamine- and cAMP-regulated neuronal phosphoprotein 32 kDa (DARPP-32), encoded by the PPP1R1B gene, is a critical signal transduction protein primarily expressed in the medium spiny neurons of the striatum [2.2.1, 2.5.1]. It functions as a molecular switch that integrates signals from various neurotransmitters, including dopamine, glutamate, and adenosine, by alternating between its roles as a protein phosphatase 1 (PP1) inhibitor and a protein kinase A (PKA) inhibitor [2.2.2, 2.3.2]. When phosphorylated at Threonine-34 by PKA, it inhibits PP1, thereby amplifying downstream signaling; conversely, when phosphorylated at Threonine-75 by Cdk5, it inhibits PKA, dampening the signal [2.3.1, 3.4.3]. This bidirectional regulation is essential for synaptic plasticity, motor control, and reward-related behaviors [2.3.2, 2.4.3]. Dysregulation of DARPP-32 signaling is implicated in numerous neuropsychiatric conditions, such as schizophrenia, Parkinson's disease, and drug addiction, as well as in the progression of various cancers where a truncated isoform (t-DARPP) is often overexpressed [2.3.1, 2.5.1]. While few drugs target DARPP-32 directly, its phosphorylation state is a key mediator of the effects of psychostimulants (e.g., cocaine), antipsychotics (e.g., haloperidol), and dopaminergic therapies (e.g., L-DOPA) [2.4.3, 3.4.1]. Consequently, DARPP-32 is considered a major regulatory hub and a potential therapeutic target for modulating neural plasticity and treating dopamine-dependent pathologies [2.4.1, 3.3.3].

Other names

PPP1R1BProtein phosphatase 1 regulatory subunit 1BDARPP32Protein phosphatase 1 regulatory inhibitor subunit 1B

DARPP-32 acts as a molecular switch that integrates neurotransmitter signals. Phosphorylation at Thr34 by PKA (stimulated by D1 receptors) converts it into a potent inhibitor of Protein Phosphatase 1 (PP1), while phosphorylation at Thr75 by Cdk5 converts it into an inhibitor of PKA. Drugs modulate these phosphorylation states to regulate neuronal excitability and synaptic plasticity.