DESCRIPTION (provided by applicant): The candidate has a three-year post-doctoral experience and is currently being proposed for an Associate Research Scientist appointment at the School of Medicine of Yale University. This application for a mentored K01 award is submitted with the goal of providing the candidate with the further training experience to function as an independent investigator working in the field of molecular biology and biochemistry of the liver. The project's long-term objective is to advance our understanding of nitric oxide (NO) signaling in liver physiology and pathophysiology. This is important for developing novel strategies to treat complications associated with liver diseases, since abnormal NO production by endothelial NO synthase (eNOS) plays a key role in vascular abnormalities observed in portal hypertension in liver cirrhosis. S-nitrosylation of proteins is an emerging area of investigation for NO-mediated physiological responses. We propose to investigate the mechanisms of S-nitrosylation, focusing on subcellular localization of eNOS and NO production, and identify the profiles of S-nitrosylated proteins in endothelial cells and liver cells using a proteomic approach. Our preliminary results suggest that there is a high concentration of NO gas at the eNOS localized area on the Golgi. This leads us to hypothesize that a gradient of NO formed in proximity to eNOS on the Golgi may be favorable to S-nitrosylation of proteins. The candidate proposes to 1) Elucidate if eNOS generates a gradient of NO in living cells, 2) Identify S-nitrosylated proteins in/on the Golgi complex using a proteomic approach, and 3) Examine protein S-nitrosylation in sinusoidal endothelial cells and hepatocytes. The Section of Digestive Diseases and the Department of Pharmacology as well as the Department of Cell Biology at Yale University are ideal for carrying out these studies because of the quality of their faculty, their experience as mentors, and the core facility at the Yale Liver Center. The School of Medicine has pledged protected time for the candidate during this further training period prior to functioning as an independent investigator.