Title | ARPP-21, a cyclic AMP-regulated phosphoprotein enriched in dopamine-innervated brain regions. I. Amino acid sequence of ARPP-21B from bovine caudate nucleus. |
Publication Type | Journal Article |
Year of Publication | 1989 |
Authors | Williams KR, Hemmings HC, LoPresti MB, Greengard P |
Journal | J Neurosci |
Volume | 9 |
Issue | 10 |
Pagination | 3631-7 |
Date Published | 1989 Oct |
ISSN | 0270-6474 |
Keywords | Amino Acid Sequence, Animals, Brain, Cattle, Caudate Nucleus, Chromatography, High Pressure Liquid, Chymotrypsin, Cyclic AMP, Dopamine, Endopeptidases, Metalloendopeptidases, Molecular Sequence Data, Phosphoproteins, Subtilisins, Trypsin |
Abstract | ARPP-21 (cAMP-regulated phosphoprotein, Mr = 21,000 as determined by SDS-PAGE) is a major cytosolic substrate for cAMP-stimulated protein phosphorylation in dopamine-innervated regions of the rat CNS. It has recently been purified to homogeneity from bovine caudate nucleus and characterized (Hemmings and Greengard, 1989). ARPP-21 is isolated as 2 isoforms, ARPP-21A and ARPP-21B. The amino acid sequence of purified bovine ARPP-21B has now been determined by gas-phase sequencing. The S-14C-carboxymethylated protein was subjected to enzymatic cleavage with trypsin, chymotrypsin, subtilisin, and endoproteinase Lys-C. The resulting peptides were purified by high-performance liquid chromatography, and selected peptides were subjected to amino acid analysis and/or amino acid sequencing by automated Edman degradation. ARPP-21B consists of a single NH2-terminal blocked polypeptide chain of 88 residues, with a calculated molecular mass of 9561 Da, including an NH2-terminal acetyl group inferred by deblocking with an acylaminopeptidase. This molecular mass is significantly lower than earlier estimates based on SDS-PAGE or hydrodynamic measurements. The seryl residue phosphorylated by cAMP-dependent protein kinase (Hemmings et al., 1989) is located at position 55. The molecule contains 1 cysteinyl residue, at position 71, and contains no methionyl, tyrosyl, phenylalanyl, tryptophanyl, or histidinyl residues. Determination of the primary structure of ARPP-21, one of several phosphoproteins localized to dopaminoceptive neurons in the basal ganglia, provides a framework for further investigations into the molecular mechanisms involved in dopaminergic neurotransmission. |
Alternate Journal | J. Neurosci. |
PubMed ID | 2552036 |
Grant List | GM-31539 / GM / NIGMS NIH HHS / United States MH-40899 / MH / NIMH NIH HHS / United States |