title: DARPP-32, a dopamine- and adenosine 3':5'-monophosphate-regulated neuronal phosphoprotein. I. Amino acid sequence around the phosphorylated threonine.
abstract: DARPP-32 (dopamine- and cyclic AMP-regulated phosphoprotein, Mr = 32,000) is a major endogenous cytosolic substrate for dopamine- and cyclic AMP-stimulated protein phosphorylation in neurons of the basal ganglia of mammalian brain. It shares many properties with phosphatase inhibitor 1, a substrate for cyclic AMP-dependent protein kinase, and with G-substrate, a substrate for cyclic GMP-dependent protein kinase. We have, therefore, undertaken an analysis of the amino acid sequence around the site at which purified DARPP-32 is phosphorylated by the catalytic subunit of cyclic AMP-dependent protein kinase. The results indicate that DARPP-32 is phosphorylated at a single threonine residue contained in the sequence Arg-Arg-Arg-Pro-Thr(P)-Pro-Ala-Met-Leu-Phe-Arg. This sequence was obtained by automated solid phase sequencing of two overlapping tryptic phosphopeptides and one overlapping chymotryptic phosphopeptide which were purified by reverse-phase high-performance liquid chromatography. A 9-amino acid sequence containing the phosphorylatable threonine residue in DARPP-32 shares 8 identical residues with a sequence containing the phosphorylatable threonine residue in phosphatase inhibitor 1, and shares 5 identical residues with the two identical sequences surrounding the 2 phosphorylatable threonine residues in G-substrate. These observations support the view that DARPP-32, inhibitor 1, and G-substrate are members of a family of regulatory proteins which are involved in the control of protein phosphatase activity by both cyclic AMP and cyclic GMP, but which differ in their cellular and tissue distributions.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D002421:Caudate Nucleus / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; D046911:Macromolecular Substances; D009419:Nerve Tissue Proteins / Q000302:isolation & purification*; D009474:Neurons / Q000032:analysis; D010446:Peptide Fragments / Q000032:analysis; D010750:Phosphoproteins; D010769:Phosphothreonine / Q000032:analysis; D014357:Trypsin
chemical_list: D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; D046911:Macromolecular Substances; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; D010750:Phosphoproteins; D010769:Phosphothreonine; D014357:Trypsin