Characterization of Endothelial Nitric Oxide Synthase Serine-600 Phosphorylation

Endothelial nitric oxide synthase (eNOS) is part of a family of three nitric oxide synthase (NOS) enzymes that catalyze the production of nitric oxide (NO). NO is a gaseous, free-radical signaling molecule that has a variety of cellular and physiological functions that range from maintaining cardiovascular homeostasis to neurotransmission. The function of NO greatly depends on the concentration and is cell type specific. eNOS is the most regulated of the three NOS isoforms and the mechanisms of regulation can be through protein-protein interactions and posttranslational modifications. A connection with eNOS and the cell cycle has begun to form with recent research identifying eNOS as a substrate of cyclin-dependent kinases (CDK). CDKs are one of the regulatory elements in cell cycle progression and form a class of serine/threonine kinases. The most commonly studied and well understood posttranslational modification of eNOS is phosphorylation. This work builds on our laboratory’s discovery of a phosphorylation site – ser600 – on the autoinhibitory loop of eNOS. Our work finds a novel connection between phosphorylation at this site and mitosis