cAMP-mediated phosphorylation of the low-Km cAMP phosphodiesterase markedly stimulates its catalytic activity.

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Grant PG, Mannarino AF, Colman RW

cAMP-mediated phosphorylation of the low-Km cAMP phosphodiesterase markedly stimulates its catalytic activity.

Proc Natl Acad Sci U S A. 1988 Dec;85(23):9071-5.

PubMed ID

2461561 [ View in PubMed

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Abstract

Treatment of intact human platelets with the adenylate cyclase agonist forskolin (100 microM) resulted in an increase in cAMP phosphodiesterase activity in freeze-thaw lysates. When the low-Km (high affinity), cGMP-inhibited cAMP phosphodiesterase was isolated from such lysates by blue dextran-Sepharose chromatography, the specific activity of the enzyme was increased an average of 11-fold over similarly processed control platelets. The increase in the low-Km, cGMP-inhibited cAMP phosphodiesterase activity was inhibited when platelets were incubated with the protein kinase inhibitor H-8 prior to treatment with forskolin, suggesting that the stimulation of cAMP phosphodiesterase activity involved a cAMP-dependent phosphorylation. When intact platelets that had been prelabeled with 32Pi were treated with forskolin and the low-Km, cGMP-inhibited phosphodiesterase was isolated by blue dextran-Sepharose chromatography, a protein of 110,000 kDa was phosphorylated. By using a monospecific antiserum to the purified phosphodiesterase, this protein was shown to be the low-Km, cGMP-inhibited cAMP phosphodiesterase by electrophoretic transfer blot (Western blot) analysis and by immunoprecipitation. The stable prostacyclin analog iloprost also stimulated the low-Km cAMP phosphodiesterase activity about 2-fold and caused phosphorylation of the enzyme. These results suggest that phosphorylation of the low-Km, cGMP-inhibited phosphodiesterase may be an important regulatory mechanism for this enzyme in platelets.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Iloprost	cAMP-specific 3',5'-cyclic phosphodiesterase 4A	Protein	Humans	Unknown	Inducer	Details
Iloprost	cAMP-specific 3',5'-cyclic phosphodiesterase 4B	Protein	Humans	Unknown	Inducer	Details
Iloprost	cAMP-specific 3',5'-cyclic phosphodiesterase 4C	Protein	Humans	Unknown	Inducer	Details
Iloprost	cAMP-specific 3',5'-cyclic phosphodiesterase 4D	Protein	Humans	Unknown	Inducer	Details