Phosphatidate (PA) phosphatase (3-sn-phosphatidate phosphohydrolase, EC 3.1.3.4) in the yeast Saccharomyces cerevisiae catalyzes the dephosphorylation of PA to form diacylglycerol and Pi. PA phsophatase plays a role in the regulation of phospholipid and triacylglycerol synthesis in S. cerevisiae. Two membrane- associated forms (45-kDa and 104-kDa) of PA phosphatase have been purified and characterized in our laboratory. In this grant application we propose to initiate a project to clone the structural genes for the 45-kDa and 104-kDa forms of PA phosphatase. We will use specific antibodies to the enzymes and lambda-ZAP cDNA expression and lambda-DASH genomic expression libraries. The cloned genes will be characterized and the essential nature of PA phosphatase will be addressed. %%% The enzyme phosphatidate (PA) phosphatase in the yeast Saccharomyces cerevisiae catalyzes the removal of phosphate from the phospholipid PA to form the neutral lipid diacylglycerol. This enzyme plays a role in the control of overall lipid synthesis in yeast and in animal cells. Two membrane-associated forms (45-kDa and 104-kDa) of PA phosphatase have been purified and characterized in our laboratory. In this grant application we propose to initiate a project to isolate the genes which encode for the 45-kDa and 104-kDa forms of PA phosphatase. We will use specific antibodies to the enzymes and DNA expression libraries in lambda viruses. Once isolated the genes for these enzymes will be characterized. The essential nature and role of these genes in yeast lipid synthesis and cell growth will be examined.
