Dopamine- and cyclic AMP-regulated phosphoprotein 32 kDa (DARPP-32) (DARPP-32)

DARPP-32 is a 32 kDa phosphoprotein highly enriched in medium spiny neurons of the striatum, where it acts as a key integrator of dopamine and glutamate signaling. Its phosphorylation state, regulated by multiple kinases and phosphatases, determines whether it inhibits PP1 (promoting protein phosphorylation) or PKA (reducing cAMP signaling). This dual regulatory capacity allows DARPP-32 to function as a molecular switchboard, modulating the response of neurons to neurotransmitters, drugs, and environmental stimuli. DARPP-32 is essential for normal striatal function, reward processing, and behavioral responses to both natural and pharmacological stimuli. Abnormalities in DARPP-32 expression or phosphorylation are linked to neurological and psychiatric disorders, as well as certain cancers. Its complex regulation and central role in multiple signaling pathways make it a challenging but important potential therapeutic target.

Other names

Protein phosphatase 1 regulatory subunit 1BPpp1r1bPhosphoprotein phosphatase-1 regulatory subunit 1BDopamine and cAMP-regulated phosphoprotein of 32 kDa

DARPP-32 is a bifunctional phosphoprotein that, when phosphorylated at threonine-34 (by cAMP-dependent protein kinase, PKA), acts as a potent inhibitor of protein phosphatase 1 (PP1); when phosphorylated at threonine-75 (by cyclin-dependent kinase 5, CDK5), it inhibits PKA. Its activity is modulated by dopamine via D1 receptors (increases Thr34 phosphorylation), glutamate (can both increase and decrease Thr34 phosphorylation via different pathways), and calcium (modulates dephosphorylation via calcineurin/PP2B and PP2A). Additional phosphorylation at serine-137 (by casein kinase 1, CK1) and serine-102 (by casein kinase 2, CK2) further fine-tunes its activity, creating a signaling hub that integrates multiple neurotransmitter inputs.