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Inhibitors of protein phosphatase-1. Inhibitor-1 of bovine adipose tissue and a dopamine- and cAMP-regulated phosphoprotein of bovine brain are identical.

TitleInhibitors of protein phosphatase-1. Inhibitor-1 of bovine adipose tissue and a dopamine- and cAMP-regulated phosphoprotein of bovine brain are identical.
Publication TypeJournal Article
Year of Publication1989
AuthorsStrålfors P, Hemmings HC, Greengard P
JournalEur J Biochem
Volume180
Issue1
Pagination143-8
Date Published1989 Mar 1
ISSN0014-2956
KeywordsAdipose Tissue, Amino Acids, Animals, Brain, Cattle, Chromatography, Gel, Chromatography, High Pressure Liquid, Cross Reactions, Cyanogen Bromide, Cyclic AMP, Dopamine, Dopamine and cAMP-Regulated Phosphoprotein 32, Electrophoresis, Enzyme Inhibitors, Muscles, Nerve Tissue Proteins, Peptide Mapping, Phosphoprotein Phosphatases, Phosphoproteins, Phosphorylation, Precipitin Tests, Protein Phosphatase 1, Rabbits
Abstract

Protein phosphatase inhibitor-1 was purified from bovine adipose tissue. The protein had an apparent molecular mass of 32 kDa by SDS/PAGE and a Stokes' radius of 3.4 nm. It was phosphorylated by cAMP-dependent protein kinase on a threonyl residue; this phosphorylation was necessary for inhibition of protein phosphatase-1. Bovine adipose tissue inhibitor-1 was compared directly with rabbit skeletal muscle inhibitor-1 and with a 32000-Mr, dopamine- and cAMP-regulated phosphoprotein from bovine brain (DARPP-32), also an inhibitor of protein phosphatase-1. By the following biochemical and immunochemical criteria, bovine adipose tissue inhibitor-1 was found to be very similar and possibly identical to DARPP-32 and was clearly distinct from skeletal muscle inhibitor-1: molecular mass by SDS/PAGE; Stokes' radii; phosphorylation on threonine residues; Staphylococcus-aureus-V8-protease-generated peptide patterns analyzed by SDS/PAGE; tryptic phosphopeptide maps analysed by two-dimensional thin-layer electrophoresis/chromatography; elution on reverse-phase HPLC; chymotryptic peptide maps as analysed by reverse-phase HPLC; amino acid composition; antibody recognition by immunoprecipitation and immunoblotting; effect of cyanogen bromide cleavage on protein phosphatase inhibitor activity. Based on these results we conclude that bovine brain and adipose tissue contain an identical phosphoprotein inhibitor of protein phosphatase-1 (DARPP-32), which is distinct from that of skeletal muscle (inhibitor-1).

Alternate JournalEur. J. Biochem.
PubMed ID2540000
Grant ListMH-40899 / MH / NIMH NIH HHS / United States