Yeast V-ATPase Regulation by Phosphofructokinase-1

V-ATPase is a vacuolar (lysosome-like) ATPase-dependent proton pump necessary for maintaining pH homeostasis in the organelles of the endomembrane system. It also contributes to regulation of the cytosol pH and the extracellular pH. In specialized cells (renal intercalated cells, epididymis clear cells, and osteoclasts), V-ATPase proton transport supports urinary acidification, sperm maturation, and bone resorption. Genetic mutations of V-ATPase expressed in those tissue-specific cells cause distal renal tubular acidosis, infertility, and osteopetrosis. V-ATPases are composed of a peripheral domain (V1), which hydrolyzes ATP, and a membrane-bound domain (Vo), which transports proton. V-ATPase activity is tightly regulated in vivo by numbers of mechanisms, including reversible disassembly of the V1 and Vo domains. Glucose, the nutrient oxidized in glycolysis, modulates reversible dissociation of V-ATPase. This dissertation was aimed at understanding how subunits of phosphofructokinase-1 (α subunit and β subunit) regulate V-ATPase function. Our results showed that both subunits are important for V-ATPase activity, but β subunit displayed more significant phenotypes. Deletion of β subunit reduced glucose-dependent V1Vo reassembly and altered V-ATPase binding to its assembly factor, RAVE. We additionally investigated the mechanisms by which phosphofructokinase-1 controls V-ATPase function. We concluded that glucose-dependent V1Vo reassembly and V-ATPase function at steady state were controlled by the glycolytic flux, independently of phosphofructokinase-1. Notably, V-ATPase activation in vivo correlated with the presence of phosphoglycerate kinase at vacuolar membranes. These studies further advanced our understanding how glucose controls V-ATPase pumps in vivo

Employees‟ Perception on their Superiors‟ Leadership style and its relationship with Fostering Innovation Culture in Manufacturing Industry in Penang, Malaysia.

Kajian kuantitatif adalah untuk meramalkan hubungan antara gaya kepimpinan pemimpin memupuk budaya inovasi. This quantitative study was to predict the relationships between the leaders‟ leadership styles on fostering innovation culture

A Fallacy of Division: The Failure of Market Concentration as a Measure of Competition in U.S. Banking

Empirical literature and related legal practice using concentration as a proxy for competition measurement are prone to a fallacy of division, as concentration measures are appropriate for perfect competition and perfect collusion but not intermediate levels of competition. Extending the classic Cournot-type competition model of Cowling and Waterson (1976) and Cowling (1976) used to derive the Hirschman-Herfindahl Index (HHI) of market concentration, we propose an adaptation of this model that allows collusive rents for all, none, or some of the firms in a market. Application of our model to data for U.S. commercial banks in the period 1984-2004 confirms that concentration measures are unreliable competition metrics. While collusion is prevalent in the banking industry at the state level, the critical market shares at which market power is achieved, rents earned from collusion, and collusive concentration levels vary widely across states. These and other results lead us to conclude that a fallacy of division exists in concentration-based competition tests.SCP hypothesis, competition, Cournot, conjectural variation, efficiency hypothesis