Phosphatidate (PA) phosphatase, the enzyme that catalyzes the penultimate step in triacylglycerol synthesis, is a cytosolic enzyme that must associate with the membrane where its substrate PA resides. Fluorescence spectroscopy was used to measure the interaction of yeast PAH1-encoded PA phosphatase with model liposome membranes. PA phosphatase contains five tryptophan residues and exhibited inh...

Neil Grimsey, Gil-Soo Han, Laura O’Hara, Justin J. Rochford, George M. Carman, and Symeon Siniossoglou From the Cambridge Institute for Medical Research, University of Cambridge, Hills Road, CB2 0XY Cambridge, United Kingdom, the Department of Food Science and Rutgers Center for Lipid Research, Rutgers University, New Brunswick, New Jersey 08901, and the Department of Clinical Biochemistry, Uni...

BACKGROUND Phosphatidate phosphatase (PAP) plays diverse roles in lipid metabolism and cell signaling. RESULTS A novel yeast PAP is identified as the actin patch protein encoded by APP1. CONCLUSION APP1 and other known genes (PAH1, DPP1, LPP1) are responsible for all detectable PAP activity in yeast. SIGNIFICANCE Identification of App1p as a PAP enzyme will facilitate the understanding of...

Rat hepatocytes were incubated in monolayer culture in modified Leibovitz L-15 medium containing either 10% (v/v) newborn-calf serum or 0.2% (w/v) fatty-acid-poor bovine serum albumin. The addition of 100 nM-dexamethasone increased the activities of both phosphatidate phosphohydrolase and tyrosine aminotransferase by about 3.5-fold after 8h, and these activities continued to rise until at least...

At 24-26 degrees C, force-area isotherms show that unionized dipalmitoyl phosphatidic acid forms a solid-condensed film while unionized egg and dioleoyl phosphatidic acids form liquid-expanded films. Surface area is a characteristic feature of a specific phosphatidic acid and the purity of a phosphatidic acid preparation can be established by the surface area of the unionized phosphatidic acid ...