DARPP-32 (dopamine- and cAMP-regulated phosphoprotein with an apparent Mr of 32,000), now also known as phosphatase 1 regulatory subunit 1B (PPP1R1B), is a potent inhibitor protein (PP1, PPP1) when phosphorylated at Thr34 by cAMP-dependent kinase (PKA). exhibits remarkable regional distribution in brain, roughly similar to that dopamine innervation. Its discovery was culmination the long-standi...