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Neuropharmacology. 1994 Nov;33(11):1245-51.

Cyclic nucleotide dependent phosphorylation of neuronal nitric oxide synthase inhibits catalytic activity.

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1
Department of Medicine (Division of Cardiology), Johns Hopkins University School of Medicine, Baltimore, MD 21205.

Abstract

We have examined the regulation of neuronal nitric oxide synthase (NOS) by phosphorylation with cyclic-GMP (PKG) and cyclic-AMP-dependent (PKA) protein kinases. In vitro phosphorylation studies indicate that both PKG and PKA phosphorylate NOS on a single site. Phosphoamino-acid analysis and peptide mapping demonstrate that phosphorylation by either cyclic-nucleotide kinase occurs on a similar serine residue. Phosphorylation of purified NOS by either PKG or PKA diminishes catalytic activity. Stimulation by 8-Br-cGMP of HEK-293 cells stably transfected with the cDNA for neuronal NOS (293.NOS cells) results in phosphorylation of immunoprecipitated NOS. Incubation of 293-NOS cells with 8-bromo-cGMP or dibutyryl-cAMP reduces nitrite release in response to stimulation with calcium ionophore A23187. Phosphorylation-induced decreases in NOS activity may counterbalance and modulate NOS activating signals.

PMID:
7532810
[Indexed for MEDLINE]
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